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CHAPTER 1
INTRODUCTION
1.1BACKGROUND STUDY
From the beginning when motor engines were first invented, people started to make from it ideas to carry groups of people on long distance. Nowadays buses travel all over the world and take an important place in global economy and transportation. Only in Europe coach transportation brings 15 billion Euros per year. On the short or middle distances, they are the cheapest mode for traveling. The variety of types provide a wide selection of services from long distance trips to couple hour excursion around city sightseeing. Company of bus organizes trips and safe carry of the passengers meet everyday challenges in security, safety and most importantly comfort sectors.
Bus transportation is on the second place by carrying after air flights and it is one the safest modes of travel. Bus equipment and size depends on usage purpose and climate features. Long distance buses must have comfortable seats with an option for sleeping and meal consumption. Therefore, the air conditioning had been placed and variety of improvement be done to satisfy passenger requirement. If ten year ago these options were expensive and rare, today all buses have them as necessary options. The only exclusion is that not all countries still can afford modern buses (Moskvitch K.2015).

Buses are designed and used already for hundred years to carry a big number of passengers. The word “bus” is coming from old Latin word “omnibus” and other older words like “autobus”, “multibus”. The main meaning of “omnibus” is “for everyone”. The reason for making this type of vehicle is to bring the group of people from one point to another with low cost and spending. It means that the bus can use all classes of people. The first coach line was organized by the French entrepreneur, who wanted to stimulate the society to visit his bathhouse. After this idea, the bus line found their places in other cities of France, England, and Europe. Those were pulled by horses and established between 1824 and 1825. Motor buses firstly were established at the end of 19th century. From that time transportation started to develop rapidly. Today there are large numbers of bus varieties depending on the use. However, among all of them, some types are ancestors. Those are like single-decker and double-decker. Since it develops very fast, today there are a huge amount of bus types.
As it was mentioned earlier, bus development very fast. Bus nowadays receive good comment from the passenger as for the excellent comfort condition. It is because modern bus use air conditioning widely compares to a few years previously. Many improvements of air conditioning in the bus have been done especially in ducting size and design. Bus ducting design is one of the hardest systems to install as lack of space always become an issue to deal with. Different types of a bus will require different layout of a ducting system to fit the space requirement meanwhile focused on customer satisfaction. Misplaced supply ducts and ducting design will be resulting in discomfort.
The air conditioning system for the bus should be selected considering several parameters including passenger capacity, local climate, and fuel consumption. It is possible to determine whether a selected air conditioning system provides desired performance through testing.
1.2PROBLEM STATEMENT
One of the frequent problems of bus air conditioning is an unbalanced distribution of air flow especially when climax condition and full load passenger. Sometimes, some comment arises complain that big size of ducting affected to high fuel consumption and luggage compartment.
1.3OBJECTIVE
The objective of this research is:
To study and analyze air distribution pattern for an automobile vehicle.

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To modified and propose new ducting design with thermal enhancement.

1.4PROJECT SCOPE
This project is based on industry problem and will be carried out in Pioneer CoachBuilder, Pelabuhan Klang. Measurement for the parameter in ducting design will be taken and analyze the thermal enhancement that affects comfort condition for a passenger in a bus. A parameter that will be considered such as air velocity, bus design structure, temperature, airflow distribution, number of seat in bus, ducting design and duct material used. This project will focus on single decker bus type that using rooftop mounted with forty to forty-five number of passenger. A possible modification for ducting design will be analyzed and stimulate using Hyperwork software.
CHAPTER 2
LITERATURE REVIEW
2.1INTRODUCTION
This chapter review related journals and researchers on the transportation air conditioning ducting and various concepts for thermal enhancement in detail. Generally, air conditioning in the transportation industry exemplifies how modern technology has increased the comforts of people everyday life. Air conditioning has been employed in many types of transport such as trains, cars, and buses. For air to be delivered to the air-conditioned space there is need to use air carriers which are known as the ducts. Basically, the ducting system in each type of transportation is difference specializes in the development, design, test, production, supply, and service of heating, ventilation and air conditioning systems for the number of occupants. These systems also include the power supply, pressure protection, air ducts and control equipment. The development of air conditioning system in transportation obviously to provide a comfortable environment and required thermal comfort for the transportation. Therefore, this chapter will describe the finding from the investigation that has been carried out by several researchers which are focused on transportation air conditioning ducting system which is bus and thermal enhancement for a comfortable environment.
2.2BUS AIR CONDITIONING SYSTEM
Bus air conditioning defined as the cooling, dehumidification, and filtration of the air within the passenger compartment inside the bus. The system of air conditioning in bus mainly consists of a compressor, condenser, evaporator, magnetic clutch, alternator, fresh air device, blower, fan, return air grille, control panel, pipeline system and electric-controlled system. The reservoir, filter drier, sight glass, cut off valve, expansion valve and fresh air device are in the interior of the evaporator. The compressor is mounted on the side of the engine, and the climate control panel of the bus air conditioning system has its own starting system, which is located beside of the instrument board. As for the condenser, it mainly divided into new design multi-flow condenser, traditional copper and fin condenser. Condenser fan blows the air through the condenser coil to aid the heat dissipation better. Figure 2.1 shows the component that involves a bus air conditioning refrigeration cycle.

Figure 2.1 Component of bus air conditioning
Bus air conditioning refrigeration cycle starts when the thermostat that located in the interior calls for cooling. When thermostat starting give a signal, the electromagnetic clutch on the compressor engages. Once engaged, the compressor then circulates refrigerant through the system through interconnecting hoses. The refrigerant that existing as a gas and containing the heat from the passenger compartment is pump by the compressor under high pressure into the condenser coil. Fan pull cool air through the condenser coil, which contains refrigerant existing as a hot gas. The refrigerant undergoes a change of state from a gas to a liquid through a process called condensation. During condensation, the hot gas rejects its heat load to the outside air which was transferred from the passenger compartment into the refrigerant by the evaporator. Then, the refrigerant now exists as a cool liquid which passes through the filter drier, which removing moisture and impurities, and then the sight glass, which enables visual inspection of the refrigerant. The cool liquid is then pumped to the evaporator where an expansion valve meters the refrigerant into the evaporator coil. Fans pull passenger compartment air through a filter which removes particulate matter and then passes the cleaned air through the evaporator coil. The refrigerant undergoes a change of pressure from high to low and corresponding change of state from a liquid to a gas through a process called evaporation. During evaporation, the heat contained in the air in the passenger compartment is absorbed by the gaseous refrigerant. A warm air passes through the evaporator coil, moisture condenses and is collected and drained to the exterior of the bus. Finally, the hot gas is then suctioned back to the compressor and pumped to the condenser to keep the refrigerating cycle.
2.2.1Types of System
2.2.1.1Rooftop Mounted
Roof mounted air conditioner unit suitable for mounting on the roof of a vehicle which has a passenger compartment and air delivery ducts and is adapted for delivery of conditioned air from the air conditioner unit into the passenger compartment such as a bus. Roof mounted air conditioner units which incorporate both the evaporator and condenser functions in a single package quite often limit heat exchanger coil surface area, condenser coil surface area limiting the capacity of the limit. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1007/s11113-013-9277-6”, “ISBN” : “1111301392776”, “ISSN” : “1047-2797”, “author” : { “dropping-particle” : “”, “family” : “Engineering”, “given” : “Earthquake”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “19”, “issued” : { “date-parts” : “2002” }, “page” : “1-26”, “title” : “I . u . s . s .”, “type” : “article-journal”, “volume” : “32” }, “uris” : “http://www.mendeley.com/documents/?uuid=c1833c64-47a0-4160-b7b5-b41293653d76” } , “mendeley” : { “formattedCitation” : “(Engineering, 2002)”, “plainTextFormattedCitation” : “(Engineering, 2002)”, “previouslyFormattedCitation” : “(Engineering, 2002)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Engineering, 2002)

Figure 2.2.1.1 Rooftop mounted
2.2.1.2 Rear Mounted
Rear mounted air conditioner is located on the rear wall of the bus and arrange to exchange conditioned air for return air drawn from the buses passenger compartment through a central opening in the rear wall of the bus. A housing is mounted over the central opening inside the bus that has a front wall that extends to either side of the opening. The opening in the rear wall is typically situated directly over a row of seats located along the rear wall of the bus. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.(73)”, “ISBN” : “2004001828”, “ISSN” : “2004001828”, “PMID” : “1000182772”, “author” : { “dropping-particle” : “”, “family” : “Kong”, “given” : “Shiao-tong”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Application”, “given” : “Foreign”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Data”, “given” : “Priority”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “12”, “issued” : { “date-parts” : “2011” }, “page” : “12-15”, “title” : “( 12 ) United States Patent”, “type” : “article-journal”, “volume” : “2” }, “uris” : “http://www.mendeley.com/documents/?uuid=8452eba8-28d7-4ff5-ac83-1817cfa12827” } , “mendeley” : { “formattedCitation” : “(Kong, Application, & Data, 2011)”, “plainTextFormattedCitation” : “(Kong, Application, & Data, 2011)”, “previouslyFormattedCitation” : “(Kong, Application, & Data, 2011)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Kong, Application, & Data, 2011)

Figure 2.2.1.2 Rear mounted or sub-engine
2.3DUCTING SYSTEM OF AIR CONDITIONING
Air conditioning ducting and ducts is a type of pipe or tunnel that is used to distribute air from the air conditioner throughout a structure or building. The systems of ducts known as ductwork are the central component of a building heating, ventilation, and air conditioning system. In most air conditioning systems, only one set of ductworks is present which is used to transport cool air in summer and heated air in winter as air is required for general ventilation needs. Ducting is used only with large central air conditioning units and is not required for homes or small offices that use split systems or ductless air conditioning. Different materials can be used to manufacture air conditioning ducts. Galvanized steel sheeting is the most widely used due to its strength, low cost and resistance to rust and corrosion. For special projects, stainless steel or aluminum can also be used. Types of a duct and ducting commonly known are round ducting, square ducting, rectangular ducting, spiral ducting, stainless steel ducting, square to round rectangular ducting and plenum boxes. Air conditioning ducting is selected based on size, shape, and material. The size of duct based on air pressure in the type of HVAC equipment being used and the cooling need of the occupants. Round duct is the most efficient by allowing a greater volume of air movement per unit of duct but is rarely used. Instead, building constructors and air conditioning installers prefer square or rectangular ducts which fit more easily into a tight ceiling or wall cavities. Spiral ducting which resembles corrugated pipes is often chosen for its attractive appearance when the spiral ducts will be left exposed or painted to blend in with the environment.
To understand the need for air conditioning ducting, one must first understand how a central air system works. First, a system of intake grilles or louvers pulls fresh air from outside into the central air conditioner. The air is then cooled and blown into an air conditioning duct system where it is distributed to the various room. The cool air enters the room through air terminal units installed at the end of each ducts line which is generally taking the form of diffusers or grilles. This network of ducts that transport cool air from the air conditioning unit to each room is called the supply network. Then, to regulate the air pressure in each room, some air must be removed to make way for the new cool air supply. The second set of air conditioning duct called the return ductwork is used to remove and transport warmer air from each room back to air conditioning unit for cooling. The air enters the return ducts through exhaust grilles in each room, then travel back to the central air conditioning unit where it is cooled again for redistribution or released to the outside of the building and exchange fresh air.
2.3.1Bus Air Conditioning Ducting
For certain types of bus construction such as buses which travel relative long distance at highway speeds between stops, desire minimal airflow drags and according require that the air conditioning and air distribution system be confined within the normal outer structure of the bus. The distribution of air in a bus for heating, cooling, and fresh air circulation is a major factor in obtaining satisfactory passenger comfort. The cooling of a bus is best accomplished with air from roof ducts which extend along the outer roof corners. Meanwhile, heating of a bus is best accomplished with air from floor and sidewall ducts.

Figure 2.3.1(a) Ducting before installation

Figure 2.3.1(b) Ducting after installation
Ducts are implied in such to supply air, return air and exhaust air and usually deliver ventilation air as its parts of supply air. Duct design is the term used when planning, sizing, drawing and optimizing pressure losses are conducted. The difference in sizes, shapes, and material used in ducting of a bus is because each type of air duct proposes a different motive, strength, and limitations. Ducts in bus focused in what kind of material used and usually, the material used in ducting for a bus are aluminum, plastic, and fiber. Company objective usually to get a low cost of ducting meanwhile focusing on passenger comfort. Nowadays bus company designs a ducting compose of aluminum material as is known for its properties which is light-weight and easy to deal when it comes to installation of ductwork as shown in Figure 2.3.1(b).

Figure 2.3.1(c) Return air grille location
As shown in Figure 2.3.1, the air return is approximately at passenger compartment temperature and returning air with little or no dirt. The return air is part of an acoustical plenum which surrounds the air discharges duct where the air conditioner discharges conditioned air into the bus air duct distribution system. (Ronald W. Brown, 1989) Air grille located in the center of the bus structure so that returning air easily can be discharged. The direct discharge and elevated entry of cooled air promote a very quick pull-down which is essential for passenger comfort. An adjustable damper located in the return air duct that can be positioned to regulate the addition of outside air to the return air stream being drawn from inside the bus. (Belin Czechowicz, 2003)
2.4THERMAL COMFORT IN VEHICLE
Thermal comfort is that condition of mind which expresses satisfaction with the thermal environment. Thermal comfort is a subjective term defined by a polarity of sensations and is secured by all factor influencing the thermal condition experienced by an occupant, therefore is difficult to give a universal definition of this concept. The thermal comfort sensation is assured by the factor that depends on the heat exchange between the human body and the ambient temperature of an environment. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.egypro.2015.12.229”, “ISSN” : “18766102”, “abstract” : “This research paper presents a review of factors which influence the thermal comfort inside of vehicle. These factors can be classified in two classes: measurable factors, which include: the air temperature, air velocity, radiant temperature and relative humidity and personal factors which include: activity level and clothing insulation. An optimal level of the thermal comfort inside a vehicle can only be achieved by taking into account these measurable and personal factors. Based on these factors we can calculate Predicted Mean Vote (PMV) which represents the average thermal sensation felt by a group of people placed in the vehicle and determining the Predicted Percentage of Dissatisfied (PPD) index, which is the quantitative measure of thermal comfort of a group of people at a particular environment.”, “author” : { “dropping-particle” : “”, “family” : “Simion”, “given” : “Mihaela”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Socaciu”, “given” : “Lavinia”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Unguresan”, “given” : “Paula”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Energy Procedia”, “id” : “ITEM-1”, “issue” : “November 2015”, “issued” : { “date-parts” : “2016” }, “page” : “472-480”, “publisher” : “Elsevier B.V.”, “title” : “Factors which Influence the Thermal Comfort Inside of Vehicles”, “type” : “article-journal”, “volume” : “85” }, “uris” : “http://www.mendeley.com/documents/?uuid=9bab8565-bad9-4bf5-8ec0-94cfb1b316c9” } , “mendeley” : { “formattedCitation” : “(Simion, Socaciu, & Unguresan, 2016)”, “plainTextFormattedCitation” : “(Simion, Socaciu, & Unguresan, 2016)”, “previouslyFormattedCitation” : “(Simion, Socaciu, & Unguresan, 2016)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Simion, Socaciu, & Unguresan, 2016)
Because a human being is different, thermal comfort usually refers to set of optimal parameters for which the highest percentage possible of a group of people feel comfortable about the environment. (Lavinia Socaciu,2015) There six primary factors that must be approached when defining the condition for thermal comfort. These factors can be classified into two classes which is a measurable factor and personal factors. The measurable factors include the air temperature, air velocity, radiant temperature and relative humidity. Meanwhile, the personal factors include activity level and clothing insulation. To realize the study of thermal comfort inside the vehicle must be considered all of these because they may vary in time and because each person has a different comportment thus it is difficult to satisfy every person placed in a closed space like inside the vehicle environments. These factors are independent, but together they contribute to establishing the thermal comfort. If one factor suffers changes, then other factors need to be adjusted to maintain the thermal comfort.

Figure 2.4 Measurable and personal factor to determine the thermal comfort in a vehicle. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.egypro.2015.12.229”, “ISSN” : “18766102”, “abstract” : “This research paper presents a review of factors which influence the thermal comfort inside of vehicle. These factors can be classified in two classes: measurable factors, which include: the air temperature, air velocity, radiant temperature and relative humidity and personal factors which include: activity level and clothing insulation. An optimal level of the thermal comfort inside a vehicle can only be achieved by taking into account these measurable and personal factors. Based on these factors we can calculate Predicted Mean Vote (PMV) which represents the average thermal sensation felt by a group of people placed in the vehicle and determining the Predicted Percentage of Dissatisfied (PPD) index, which is the quantitative measure of thermal comfort of a group of people at a particular environment.”, “author” : { “dropping-particle” : “”, “family” : “Simion”, “given” : “Mihaela”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Socaciu”, “given” : “Lavinia”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Unguresan”, “given” : “Paula”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Energy Procedia”, “id” : “ITEM-1”, “issue” : “November 2015”, “issued” : { “date-parts” : “2016” }, “page” : “472-480”, “publisher” : “Elsevier B.V.”, “title” : “Factors which Influence the Thermal Comfort Inside of Vehicles”, “type” : “article-journal”, “volume” : “85” }, “uris” : “http://www.mendeley.com/documents/?uuid=9bab8565-bad9-4bf5-8ec0-94cfb1b316c9” } , “mendeley” : { “formattedCitation” : “(Simion et al., 2016)”, “plainTextFormattedCitation” : “(Simion et al., 2016)”, “previouslyFormattedCitation” : “(Simion et al., 2016)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Simion et al., 2016)
2.4.1Air temperature
Air temperature is defined as the average temperature of the air surrounding the body with respect to location and time. The air temperature inside of vehicles depends on season time and the position on the globe of a vehicle. Usually, the requirement for thermal comfort in summer conditions, interior air temperature should be around the range of 23 to 28°C. The parameters for air temperature include the mean interior temperature and the criteria for horizontal and vertical temperature distribution to reduce areas of local thermal discomfort to a minimum. The different requirement was also defined for surface temperatures. The air temperature depends on the cabin space of vehicles. At the same driving conditions, a larger vehicle may have an absolutely different air temperature than a small economy class vehicle.

2.4.2Relative humidity
Relative humidity defined as the ratio of the amount of water vapor in the air to the amount of water vapor that the air could hold at the specific temperature and pressure. The recommended values for inside temperature and air humidity correlated with the outside temperature given in Table 2.4.2.

Table 2.4.2 Values for inside temperature and air humidity in correlation with the outside temperature. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.egypro.2015.12.229”, “ISSN” : “18766102”, “abstract” : “This research paper presents a review of factors which influence the thermal comfort inside of vehicle. These factors can be classified in two classes: measurable factors, which include: the air temperature, air velocity, radiant temperature and relative humidity and personal factors which include: activity level and clothing insulation. An optimal level of the thermal comfort inside a vehicle can only be achieved by taking into account these measurable and personal factors. Based on these factors we can calculate Predicted Mean Vote (PMV) which represents the average thermal sensation felt by a group of people placed in the vehicle and determining the Predicted Percentage of Dissatisfied (PPD) index, which is the quantitative measure of thermal comfort of a group of people at a particular environment.”, “author” : { “dropping-particle” : “”, “family” : “Simion”, “given” : “Mihaela”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Socaciu”, “given” : “Lavinia”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Unguresan”, “given” : “Paula”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Energy Procedia”, “id” : “ITEM-1”, “issue” : “November 2015”, “issued” : { “date-parts” : “2016” }, “page” : “472-480”, “publisher” : “Elsevier B.V.”, “title” : “Factors which Influence the Thermal Comfort Inside of Vehicles”, “type” : “article-journal”, “volume” : “85” }, “uris” : “http://www.mendeley.com/documents/?uuid=9bab8565-bad9-4bf5-8ec0-94cfb1b316c9” } , “mendeley” : { “formattedCitation” : “(Simion et al., 2016)”, “plainTextFormattedCitation” : “(Simion et al., 2016)”, “previouslyFormattedCitation” : “(Simion et al., 2016)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Simion et al., 2016)
2.4.3Mean radiant temperature
Mean radiant temperature defined as the uniform temperature of an imaginary black enclosure which would result in the same heat loss by radiation from the person as the actual enclosure. The mean radiant temperature can be calculated if is known the surfaces, the temperature which separates the passenger area respectively the temperature and the position of every construction element around passenger inside the vehicle
2.4.4Air velocity
Air velocity defined as the average speed of the air which the body is exposed with respect the location and time. A human body is very sensitive to air movement especially in some parts like the neck, head, and feet. If the flow rate is too high or irregular, then local thermal discomfort appears. It is important to easily control the air velocity and the flow direction. The working principle of the vehicle air conditioning and ventilation system based on driving the conditioned air through adjustable air vents inside the vehicle cabin. Some studies focused on understanding how air flows through a different type of diffusers and how the people comfort can be improved by the passive control of the air jets. The air flow from the air conditioning increases the air velocity inside the vehicle and the values of the air flow velocity. The main requirement regarding a preferable combination of local air velocity and temperature system should meet are attain and keep local skin temperature within comfort range to penetrate natural air flow around the body to avoid draught or eye irritation to supply the breathing zone with the fresh clean air.

2.4.5Human activity level
A human requires energy to perform work and produce heat to maintain the internal body temperature around 36.5°C. The higher activities level is more intense, the more heat is produced. It produced too much heat, then the body will sweat which will cause discomfort. Activity level has a strong influence on human thermal sensation, comfort, and indoor temperature preferences. In table 2.4.5 are presented an estimation of metabolic rate for basic activity.

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2.4.6Clothing insulation
Clothing is needed to protect the human body against hostile climate condition and assists in the thermoregulatory of the body by maintaining the thermal balance between skin and the atmosphere. The thermal comfort is related to fabrics ability to maintain skin temperature and allow transfer of perspiration produced by the body. In table 2.4.6 are presented an estimation of some types of clothing insulation.

Table 2.4.6 Clothing level and insulation. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.egypro.2015.12.229”, “ISSN” : “18766102”, “abstract” : “This research paper presents a review of factors which influence the thermal comfort inside of vehicle. These factors can be classified in two classes: measurable factors, which include: the air temperature, air velocity, radiant temperature and relative humidity and personal factors which include: activity level and clothing insulation. An optimal level of the thermal comfort inside a vehicle can only be achieved by taking into account these measurable and personal factors. Based on these factors we can calculate Predicted Mean Vote (PMV) which represents the average thermal sensation felt by a group of people placed in the vehicle and determining the Predicted Percentage of Dissatisfied (PPD) index, which is the quantitative measure of thermal comfort of a group of people at a particular environment.”, “author” : { “dropping-particle” : “”, “family” : “Simion”, “given” : “Mihaela”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Socaciu”, “given” : “Lavinia”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Unguresan”, “given” : “Paula”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Energy Procedia”, “id” : “ITEM-1”, “issue” : “November 2015”, “issued” : { “date-parts” : “2016” }, “page” : “472-480”, “publisher” : “Elsevier B.V.”, “title” : “Factors which Influence the Thermal Comfort Inside of Vehicles”, “type” : “article-journal”, “volume” : “85” }, “uris” : “http://www.mendeley.com/documents/?uuid=9bab8565-bad9-4bf5-8ec0-94cfb1b316c9” } , “mendeley” : { “formattedCitation” : “(Simion et al., 2016)”, “plainTextFormattedCitation” : “(Simion et al., 2016)”, “previouslyFormattedCitation” : “(Simion et al., 2016)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Simion et al., 2016)
Clothing insulation could reduce the heat loss from the body and influence the heat balance which means that it could either keep the body warm or lead to overheating. A human body has a different skin temperature of each different part. By adding the layers of clothing, an occupant could try to adapt the vehicle environment as the most direct way. The main factors leading to a reduction of clothing insulation are airspeed (increased airspeed decreases clothing insulation), body movements (pumping action breaks up air layer), water vapor transfer (clothing offers a passage of water vapor and decreases heat loss by evaporation from skin).

2.5PARAMETER IN BUS AIR CONDITIONING DUCTING SYSTEM
Air distribution system inside a bus compartment is important for providing a healthy and comfortable environment to passengers. Lack of ventilation inside the bus passenger compartment causes an increased level of air contaminants and cause discomfort. (Noor Emilia, 2015) Several factors influence the design of ducting and performance of a bus ventilation system such as size of bus, types of bus, number of seats, duct material, air supply velocity, air supply temperature, the layout of the air supply diffuser and layout of the air return grille. The important parameter like temperature, air velocity, pressure and relative humidity also be considered in bus ducting system. All this parameter important to determine whether a selected air conditioning system provides desired performance as required by the occupant. (Saban Unal, 2017)

Figure 2.5 A simplified model of bus passenger compartment (Haslinda & Nazri, 2015).

2.5.1Air temperature
Air temperature is a measure of how hot or cold the air is. It is most commonly measured weather parameter. Temperature describes the kinetic energy or energy of motion of the gases that make up air. As gas molecules move more quickly, air temperature increases. Temperature is usually expressed in degrees Fahrenheit or Celsius. 0°C is equal to 32° Fahrenheit. Room temperature is typically considered 25°C which is equal 77° Fahrenheit. A more scientific way to describe temperature is in the standard international unit Kelvin. 0° Kelvin is called absolute zero. It is the coldest temperature possible and is the point at which all molecule motion stops. It is approximately equal to -273°C and -460° Fahrenheit. Temperature can be measured in numerous ways, including thermistors, thermocouples and mercury thermometers. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “Nowadays, efforts are being made to estimate the thermal comfort in vehicles by measuring each environmental parameter – air temperature, air humidity, mean radiant temperature, air velocity, human activity and clothing insulation. An optimum level of comfort in the vehicle is obtained only by using an automatic air conditioning and climate control system. The paper focuses on the analysis of the vehicle thermal comfort parameters in order to improve the measurement methods and to establish the optimum thermal comfort inside a vehicle. The paper also describes two thermal comfort models used to estimate thermal comfort inside the vehicles.”, “author” : { “dropping-particle” : “”, “family” : “Musat”, “given” : “Radu”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Helerea”, “given” : “Elena”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Acta Universitatis Sapientiae Electrical and Mechanical Engineering”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2009” }, “page” : “215-226”, “title” : “Parameters and Models of the Vehicle Thermal Comfort”, “type” : “article-journal”, “volume” : “1” }, “uris” : “http://www.mendeley.com/documents/?uuid=3f7ceeb9-4b99-4eb8-88d0-103f3a4c0f5a” } , “mendeley” : { “formattedCitation” : “(Musat & Helerea, 2009)”, “plainTextFormattedCitation” : “(Musat & Helerea, 2009)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Musat & Helerea, 2009)
2.5.2Air velocity
Air velocity is a distance traveled per unit of time and most often expressed in feet per minute (FPM). By multiplying air velocity by the area of the duct, the air volume flowing past a point in the duct per unit of time can be determined. Volume flow is generally measured in cubic feet per minute (CFM). Air velocity is measured by sensing the pressure that is produced through the movement of the air. Velocity is also related to air density with assumed constants of 70°C and 29.92 in Hg. Two common technologies to measure velocity are capacitive-based pressure sensors and anemometers. There are two types of pressure that need to be known to measure velocities such as total pressure and static pressure. Velocity pressure is calculated by taking the difference of the total pressure and static pressure. Air velocity needs to be measuring to improve system performance, increase energy efficiency, maintain proper air flow rates to ensure occupant comfort and to measure airflow for critical spaces (Brandon, 2017).

2.5.3Relative humidity
ASHRAE Standard 55 defines relative humidity as the ratio of the partial pressure of the water vapor in a gaseous mixture of air and water vapor to the saturated vapor pressure of water at a prescribed temperature. Relative humidity is measured in only one place inside the vehicle because the pressure of the water vapor is uniform in the entire vehicle. Relative air humidity is correlated with inside temperature. These two parameters influence the thermal comfort of the passenger. The recommended values for inside and air humidity in correlation with outside temperature are shown in Table 2.5.3.

Table 2.5.3 Inside temperature and air humidity as a function of outside temperature. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “Nowadays, efforts are being made to estimate the thermal comfort in vehicles by measuring each environmental parameter – air temperature, air humidity, mean radiant temperature, air velocity, human activity and clothing insulation. An optimum level of comfort in the vehicle is obtained only by using an automatic air conditioning and climate control system. The paper focuses on the analysis of the vehicle thermal comfort parameters in order to improve the measurement methods and to establish the optimum thermal comfort inside a vehicle. The paper also describes two thermal comfort models used to estimate thermal comfort inside the vehicles.”, “author” : { “dropping-particle” : “”, “family” : “Musat”, “given” : “Radu”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Helerea”, “given” : “Elena”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Acta Universitatis Sapientiae Electrical and Mechanical Engineering”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2009” }, “page” : “215-226”, “title” : “Parameters and Models of the Vehicle Thermal Comfort”, “type” : “article-journal”, “volume” : “1” }, “uris” : “http://www.mendeley.com/documents/?uuid=3f7ceeb9-4b99-4eb8-88d0-103f3a4c0f5a” } , “mendeley” : { “formattedCitation” : “(Musat & Helerea, 2009)”, “plainTextFormattedCitation” : “(Musat & Helerea, 2009)”, “previouslyFormattedCitation” : “(Musat & Helerea, 2009)” }, “properties” : { “noteIndex” : 0 }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Musat & Helerea, 2009)
CHAPTER 3
METHODOLOGY
3.1INTRODUCTION
This chapter will discuss the step and methodology from the beginning of the project until the final step. This project will conduct an analysis of thermal enhancement for transportation air conditioning ducting and propose a new ducting design that can reduce cost following standard required for bus application. A suitable instrument will be used to measure an important parameter in deciding ducting system and the result obtained will be analyzed. This project also will make some improvement on thermal comfort that affects ducting system according to the simulation that is stimulated in Hyperwork software.

3.2FLOW CHART
1590675242570START
00START

28263852385695282670718350120028225321233762281835656570717716512021205DATA COLLECTION
0DATA COLLECTION
center1449705SITE VISIT
00SITE VISIT
center849630LITERATURE REVIEW
0LITERATURE REVIEW

395224131305400

178117560325REMODELING 2D AND 3D BY AUTOCAD
00REMODELING 2D AND 3D BY AUTOCAD

2847974267334005133975351790REPEAT PROCESS
0REPEAT PROCESS

179070074295COMPUTATIONAL PROCESS BY CFD
0COMPUTATIONAL PROCESS BY CFD

2857500233680
center116840DESIRE OPTIMIZATION
0DESIRE OPTIMIZATION

2867025153035
180022545720DATA ANALYSE
DATA ANALYSE

2867025147955center309880END
END

3.3MODELLING SOFTWARE
In this project, there a few modeling software will be used such as SolidWork, AutoCAD, and Hyperwork software. This software will help to design and observe simulation created from the data obtain regarding parameter that affects the ducting design and thermal comfort condition in bus air conditioning.

3.3.1SolidWorks Software
SolidWorks is a solid modeling computer-aided design (CAD) and computer-aided engineering (CAE) computer program that runs on Microsoft Windows. SolidWorks is a solid modeler and utilizes a parametric feature-based approach. Parameters refer to constraints whose values determine the shape or geometry of the model or assembly. Parameters can be either numeric parameters such as lengths or circle diameters or geometric parameters such as tangent, parallel, concentric, horizontal and vertical. The technique is generally to sketch 2D profiles then use methods like extruding and lofting to produce the solid shape. SolidWorks software will help to design the model of bus ducting system and learn how to optimize the design to reduce model weight or size by varying model dimensions.

Figure 3.3.1 SolidWorks simulation software
3.3.2AutoCAD Software
AutoCAD is a commercial software application used to draft 2D and 3D models with the aids of the computer. AutoCAD provides its users with an intuitive user-interface that comes with built-in design layout. These layouts include numerous templates that were specifically designed for architectural planning and building construction. So, with an adequate knowledge of AutoCAD, projects that consist of designing architectural plans for construction purposes or building structures to be replicated in real time. Newest versions of AutoCAD also provide architects and builders with the analytical tools needed to analyze a structure component and troubleshoot the stress and load levels of every support structure of a virtually designed building. This means that with AutoCAD, a design of the ducting system can be carried out specific analysis to know the structure capacity and strength before replicating it on the physical site.

Figure 3.3.2 AutoCAD modeling software
3.3.3Hyperworks Software
HyperWorks is a complete CAE software made by Altair engineering. It consists all the modules of CAE modeling, meshing, and solver. It is a complete package of infinite element procedure. Pre-processing, solving and postprocessing can be done in HyperWorks software. In this project, HyperWorks software will help analyze stresses on a prototype of ducting design, suggesting areas that can be thinned or eliminated. Then the revised part is analyzing again over several iterations to get the require thermal comfort according to bus application. The data of the air velocity, air flow rate, pressure, and temperature will be measured to proceed with the next step of a simulation.
3.4SIMULATION ANALYSIS
Based on the simulation and modeling of ducting design that demonstrates in AutoCAD, SolidWorks and HyperWorks software, several analysis and observation regarding the simulation of bus ducting design will be doing to make a comparison of the suitable ducting structure. Parameter and size of ducting according to bus application also considered so that optimum thermal comfort can be obtained.
3.5MEASUREMENT
In this project, several measurements will take based on parameter and factor affecting for ducting design. Air velocity, air temperature, relative humidity, pressure, design bus structure, ducting design ducting size, ducting material and ducting weight are listed parameter and factor that needed to construct the simulation. Measurements will be taken based on the visit to Pioneer CoachBuilders Sdn Bhd factory. Some measurement based on standard bus application.

3.5.1Equipment Used
3.5.1.1Anemometer
Anemometer is used for measuring the speed of air velocity at diffuser inside the bus in static condition during the project testing as shown in Figure 3.5.1.1. the air velocity was taken in feed per minute unit (FPM).

Figure 3.5.1.1Anemometer
3.5.1.2Digital thermocouple
The thermocouple is used to measure the temperature sensor that detects the temperature inside of the bus in static condition during the project testing as shown in Figure 3.5.1.2. the temperature was taken in Celsius (°C).

Figure 3.5.1.2Digital thermocouple
3.5.1.3 Vernier caliper
Vernier caliper is a precision instrument that can be used to measure internal and external distances extremely accurately. Actual size of ducting taken during the project as shown in Figure 3.5.1.3. Output measurement readings were taken in centimeters (cm) and it is precise up to 2 decimal places.

Figure 3.5.1.3 Vernier caliper3.5.1.4Measuring tape
A tape measure or measuring tape is a flexible ruler and used to measure distance. It consists of a ribbon of cloth, plastic, fiberglass or metal strip with linear measurement marking. Measuring tape used to measure the size of bus structure and length of ducting in this project as shown in figure 3.5.1.4. measuring tape comes in both imperial unit (inch and feet) and metric (centimeters and meter).

Figure 3.5.1.4 Measuring tape
3.5.2Measurement precaution
Some precautions will be considered before taking the measurement to avoid an error on measurement results:
The vernier caliper and measuring tape will be calibrated properly to provide precision and accuracy in data obtained.
Anemometer reading recorded in the certain time taken for a reading.

Thermocouple handling with care and use correct step of taking data
Avoid reflective object in the measurement field
3.6ANALYSE DUCTING DESIGN AND DISCUSS RESULT
After the measurement process, the data have been recorded will insert in table form. The table developed based on the parameter of the projects. Simulation analysis will be done to analyze a various ducting design and propose a new ducting design that follows standard bus application. Each simulation of ducting design will be discussed and analyze the thermal enhancement for the ducting whether this can result in a low-cost production of new ducting design with right predicted value or not.
CHAPTER 4
INITIAL RESULT AND DISCUSSION
4.1INTRODUCTION
This chapter will discuss the data that have been recorded based on parameter affecting ducting design for bus air conditioning ducting system. Data that have been recorded will insert into table form. The table developed based on the parameter of the project. With the data recorded, analysis by a simulation will be done. Each analysis of simulation regarding ducting design will be testing and analyze the thermal enhancement. This project is industry problem and what expected is a modification of ducting design will result in low-cost production with right predicted value. The modification will be done by reducing ducting weight and size in a simulation by Hyperwork software. As the expected outcome, the new ducting design will be successfully modified when reducing its weight and size. This also will result in a low-cost production of ducting design with thermal enhancement.

CHAPTER 5
CONCLUSION AND RECOMMENDATION
5.1CONCLUSION
Based on the project, the objective of this project was achieved which is to study the air distribution pattern for an automobile vehicle. The air conditioning system for bus selected considering several parameters including passenger capacity, local climate, and fuel consumption. The air distribution pattern in bus affected by the bus ducting design, temperature, bus structure design, number of passenger and duct material used. To study the air distribution in the bus, all these parameters consider important to know. Then, the main objective of this project is to be modified and propose new ducting design with thermal enhancement. For bus, different types of the bus will require different layout of the ducting system to fit the space requirement meanwhile focused on customer satisfaction. The modification of ducting design carries out in Hyperwork Software by reducing weight and size of ducting. The customer usually complains that the ducting was too big and make space smaller, but the industry objective is to get low-cost production with right predicted value. The objective achieved when the modification of ducting done with expected optimization.

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