EPH - International Journal of Science and Engineering

Transcription

1 HVAC DUCT DESIGN KARTHIKEYAN N 1,PUGALARASU R 2, AJAYRAGUL A.G 3, RAGUNANDHAN S 4, RAHUL P 5. 1 ASSISTANT PROFESSOR, K.S.R COLLEGE OF ENGINEERING, TIRUCHENGODE, TAMILNADU, INDIA &5 B.E MECHANICAL ENGINEERING, K.S.R COLLEGE OF ENGINEERING, TIRUCHENGODE, ABSTRACT The project work has been intended to suggest suitable comfort air conditioning design for the Constructed Building as we choose according to the uses. In this construction design, cooling loads were increased significantly recently because of an increase in various types of heat sources such as electric machinery. In particular, the increased numbers of personal computers, engineering workstations, etc., which generates a large amount of heat, cause serious air conditioning problems. Heat Load Calculation and AC duct from AHU Room for the Seminar Hall is designed and Diffuser is fixed at the end of duct to allow the cooled air entering into the Room and Return Air is taken between Tiles and Ceiling and Return back to the AHU room which is shown in the design. Air cooled condenser is used to cool the Refrigerant which is flowing between AHU and Air cooled condenser, Tonnage and the CFM varies according to the capacity of the occupancy and orientation of the building. Survey of the building in particular Seminar Hall is taken approximately for which heat load and the Duct Design is made which suits the Building. Then the plant was erected, commissioned and the required conditions TAMILNADU, INDIA. were achieved by existing various controls. Once the required conditions were stabilized the plant was handed over to the client. CHAPTER I INTRODUCTION 1.1 INTRODUCTION OF THESIS Atmospheric conditions are varying in different parts of our country. The summer conditions in India are quite uncomfortable in most parts of the country and winter conditions are uncomfortable in few places of the country. So air conditioning is essential for the comfort of occupants. The project work has been intended to suggest suitable comfort air conditioning design. Human beings feel comfortable and work efficiently within a restricted set of physical conditioned of temperature, humidity, draught and fresh air requirements. Fresh air is generally required to dilute the pollutant levels and CO2 levels. Lack of environmental control in buildings may affect the health of human beings apart from reduction in efficiency and comfort level. In excessively hot climates, it is necessary to reduce temperature and humidity of supply air and in excessively climates, it is necessary to increase them. Energy efficient buildings with good thermal insulation require low volume flow rates of supply air. This may lead to non-uniform velocity and temperature

2 distribution apart from stagnation zones and accumulation of pollutants and odors due to poor recirculation. Architects and air conditioning engineers have to consider all these facts apart from providing better ambience and aesthetics. The velocity and temperature distribution in the room play a very vital role from this point of view. The purpose of air conditioning is to supply sufficient volume of clean air containing specific amount of water vapour at a temperature capable of maintaining predetermined conditions within a selected enclosure. The essential feature of comfort air conditioning system is to provide an environment, which is comfortable to the majority of the occupants. 1.2 DUCTS AND DESIGN OF DUCTS Ducts are used in heating ventilation and air conditioning to deliver and remove air. The needed air flow includes for example supply air return air and exhaust air, ducts commonly delivers ventilation air as part of supply air, as such air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort. 1.3 OBJECTIVE Objective of this project is to calculate the heat load calculation and to design the duct for the seminar hall of the college, for that many parameters are taken under the consideration in order to Calculate the heat load calculation Create the duct design for the particular CFM 1.4 ORGANISATION OF THESIS Chapter 2 deals with the literature review in which the paper and journals based on heat load calculation and duct design are elaborately explained in that chapter. Chapter 3 deals with the methodology in which the basic of air conditioner are given for the reference, formulas used to calculate the heat load calculation are also given, finally by using the formula the heat load of the seminar hall is calculated manually and it is tabulated. Chapter 4 deals with the result and discussion in which the results obtained from the heat load calculation and design of the ducts are represented in the form of tabulation. Chapter 5 deals with the conclusion of the project which is undertaken. CHAPTER-III METHODOLOGY 3.1 INTRODUCTION An air conditioning system consists of many components of mechanical and electrical equipment assembled together to produce comfortable temperature, humidity, air purity and air motion in an enclosed space. Air conditioning can be broadly classified as (1) Commercial Air Conditioning, where much importance is given to occupancy

3 (2) Industrial Air Conditioning, where prime importance is given to the productivity. The air conditioning system can be mainly classified into two groups namely. The major classification is shown in FIG ). Central air conditioning system. 2). Unitary air conditioning system. 3.2 CENTRAL AIR CONDITIONING SYSTEM: In a Central air conditioning system, all the components of the system are grouped together in one central room and conditioned air is distrubuted from the central room to the required place through extensive ductwork.the central plant requires the following components and all the components to be assembled at the same place. - cooling and dehumdifing chilled water coils - heating coils, blower with motor - sprays for cooling, dehumidifing or washing - air cleaning equipment The central station A.C. system may use one of the following methods to supply the conditioned air.. Air is conditioned in the central conditioned room and is supplied to the requred room with controlled air discharged in each room. The water is chilled in the central conditioned room and is supplied to the requred room with individual flow control. Individual evaporator in each rooms with thermostatic flow control or direct expansion system. 3.3 UNITARY AIR CONDITIONING SYSTEM All the components of the unitary air condition system are assembled in the factory itself. These assembled units are usually installed in or immediately adjacent to a zone or space to be air-conditioned. These units are commonly preferred for 1.5-ton capacity. Unitary air condition system are further classified into: 1). Window (or) room air condition system. 2). Split air condition system 3). Package air condition system Window (or) Room Air Conditioning System In this type of air condition system all the components like compressor, condenser fan, condenser and evaporator are enclosed in a single cabinet. These units are normally fitted with flush window stills, projecting out of the room supported on brackets. These requires no ducting. They are available in capacities of 0.5 ton, 1 ton, 1.5 tons and 2 tons. The capacity of 1 ton unit can cool 200 square feet of area with a ceiling height of feet Split Air Conditioning System In recent years this type of air condition system are flourished well because

4 of the following advantages.. It does not require floor space. Split air conditioners are the most adaptive air conditioners available as they can be placed anywhere. These types of air condition consists of 2 basic components, the indoor unit and out door unit. These 2 units are connected by refrigerant piping that can pass through a hole in the wall of 10 cm in dia. To avoid the noise the noisy component namely compressor and condenser fan are in the out door unit. The indoor unit can be mounted on the wall or ceiling or floor. The indoor unit consists of evaporator, evaporator blower and the thermostatic expansion valve. 3.4 SELECTION OF THE SYSTEM The selection of correct air conditioning system for a particular space or building is very critical desicion faced by the design engineer.on this desicion rests the satisfaction of the customer or occupoant and the system fittness to the building it serves. Before going to select a particular system following five factors are to be considered carefully. 3.5 INTRODUCTION TO COMPRESSOR The compressor is considered as the heart of the refrigeration system as the heart pumps the blood through the body. It acts as a pump to establish pressure difference and thus creates a flow of refrigerant from one part of the system to other TYPES OF COMPRESSORS There are 4 types of compressors are commonly applied for refrigeration duty. 1). Reciprocating compressor 2). Rotary compressor 3). Centrifugal compressor 4). Scroll compressor SELECTION OF COMPRESSOR To select a compressor for an application the following data are required. The required refrigerating capacity The design saturated suction temperature The design discharged suction temperature The actual temperature of the suction vapour entering the compressor. 3.6 INTRODUCTION TO CONDENSER Condenser is a heat exchanger in which heat transfer takes place from high temperature vapour to low temperature air or water, which is used as a cooling medium. The vapour at discharge from the compressor is superheated Classification Condensers are classified as to type of cooling medium as 1. Water cooled condenser

5 2. Air-cooled condenser 3. Atmospheric condenser 3.7 INTRODUCTION TO EVAPORATOR The evaporator is an important device used in the low-pressure side of refrigeration system. The evaporator becomes cold due to the following two reasons. The temperature of the evaporator coil is low due to the low temperature of the refrigerant inside the coil. The low temperature of the refrigerant unchanged because any heat it absorbs is converted to latent heat as boiling proceeds TYPES OF EVAPORATORS According to the type of constructions. Bare tube coil evaporator Finned tube evaporator Plate and tube evaporator Shell-in-tube evaporator 3.8 EXPANSION DEVICES THERMOSTATIC EXPANSION VALUE General: - An Expansion device in a air conditioning system normally serves two purposes. One is the thermodynamic function of expanding the liquid refrigerant from the condenser pressure to the evaporator pressure.. There are two types of expansion devices. They are: 1) Variable restriction type 2) Constant restriction type 3.9 REFRIGRANT Any substance capable of absorbing heat from another required substance can be used as refrigerant. A mechanical refrigerant, which will absorb the heat from the source and dissipate the same to the sink either in the form of sensible heat or in the form of latent heat INTRODUCTION TO AIR HANDLING UNIT Air handling units play an important role in a central station air conditioning plant where ductwork is involved. It consists of electronic motor with fan arrangement. This unit will supply a positive quantity of air over the space. Normally the pressurized air from the air-handling units will be supplied through the ducts to the conditioned room. The velocity of the air will be more at the entrance of the main duct and velocity will be gradually get reduced when it passes through the duct Branch ducts also will be provided to take the conditioned air to the required room. At the outlet of the air-handling unit, chilled water circulation is provided. This chilled water comes through the pipe from the evaporator, which is situated at the central station air conditioning plant. Thus, the chilled water removes the heat from the air. Now this water is again circulated to the evaporator. Hence the operating cycle is worked.

6 FACTORS AFFECTING THE UNIT SELECTION The parameters to be considered while selecting the air-handling units are (1). Depth of the coil (2). Number of rows in the coil (3). Coil face velocity 3.11 AUTOMATIC DAMPERS Dampers are provided on the fresh air intake, return (recirculation) air duct and exhaust outlets. It is desirable to have the velocity high enough to generate sufficient pressure drop. So that when the damper opens or close slightly that will be definite range in air volume. A face velocity 100-fpm is commonly used, but velocities up to 2000fpm are desirable on bypass dampers LOCATION The location of the air handling apparatus directly influences the economic and sound level aspects of any system FILTERS The sizing of filters should be on the basis of the manufacturers rating. To consider in the selection of filters are the initial cost maintenance (cleaning & replacement) cost and the air cleaning efficiency together with its effect on the cost of cleaning the building and the cost of the cleaning the building and the cost of replacing spoiled merchandise or products that might result from insufficiently cleaned air VARIOUS TYPES OF FILTERS There are different types of air filters, which are used for removing the dust from the air. 1. Dry filters 2. Viscous filters 3. Wet filters 4. Electric filters 5. Centrifugal dust collector The purpose of all dust removal equipment s is to remove or reduce the concentration of dust to a very small fraction of its original in the conditioned air PERFORMANCE OF TYPES OF AIR FILTER Table 3.1 Air Filters Types of filter Dry fabric (cotton wool pads) Dry fabric (fine glass wool) Efficiency of filter 25 to 30 % 50 to 75% Viscous filters 5 to 15 % Electric filters 70 to 90 % 3.14 DUCT DESIGN The conditioned air from the air conditioning equipment must be properly distributed to room or space to be conditioned in order to provide comfort and to carry the return air from the room back to the air conditioning equipment for reconditioning and recirculation.

7 CLASSIFICATION OF DUCTS Supply air duct Return air duct Fresh air duct Low-pressure duct Medium pressure duct High-pressure duct Low velocity duct High velocity duct Supply air diffuser Return air diffuser DUCT MATERIAL The ducts are usually made from galvanized from sheet metal, aluminum sheet or black steel. The mostly used material is galvanized sheet metal because the zinc coating of this metal prevents rusting and avoids the cost of painting RULES FOR DUCT DESIGN A few general rules are stated below which should be followed in the design of ducts. 1. Air should be conveyed as directly as possible to economies on power, material and waste 2. Sudden changes in directions should be avoided. When bends are essential, turning vanes should be used to minimize the pressure loss. Air velocities in ducts should be within permissible limits to minimize the noise. 3. Rectangular ducts should be made as nearly square as possible. An aspect ratio of 4:1 or less should be maintained. 4. Ducts should be made of smooth materials such as galvanized iron or aluminum. Whenever other materials are used allowance should be made for roughness of the material. 5. Dampers must be provided in each branch outlet for balancing the systems. Duct obstructions are to be avoided DUCT DESIGN METHOD: There are mainly three methods, which are used to design the duct INTRODUCTION TO COOLING LOAD CALCULATIONS The rate at which heat is to be removed from a space to bring and maintain it at desired conditions is called cooling load. The successful performance of the air conditioning and refrigeration plants depends on the accuracy in arriving cooling load BASIS OF DESIGN The basis of design depends on outdoor design conditions for various localities and inside design conditions for various applications. The design conditions directly affect the load and intern affect the equipment selection.

8 Out Door Design Conditions The choice of outdoor DBT and WBT for different types of application varies as outlined below Normal Design Conditions Summer Normal design conditions are recommended for use with comfort and industrial cooling application, where it is occasionally permissible to exceed the design room condition. Maximum design conditions are recommended for laboratories and industrial application. Where exceeding the design conditions for even shorter periods of time can be detrimental by product or process. Customer has furnished climatic conditions of Salem as below, to be considered for design of HVAC system. Table 3.2 Climate Condition in Salem Sr. No. Description Dry Bulb Temperature (ºF) Wet Bulb Temperature (ºF) 1 Summer Monsoon Inside Design Conditions Inside design conditions are vary with application. The conditions are based on experience gathered from many applications substituted by tests, while selecting inside conditions client suggestions are taken into consideration. Relative Humidity (%) 3.17 LOAD ESTIMATION The cooling equipment provided must be able to remove heat at the rate at which it is produced and maintain the given comfort conditions in the room. It must take into account the heat coming in to the space from out door on a design day, as well as the heat being generated within the space. The following sources contribute to the heat load for a conditioned room. Solar transmission through wall and roof. Solar heat gain through glass. Heat transmission gain through partition, ceiling, floor and glass. Infiltration and ventilation load. Internal and system heat gain Solar Transmission through Wall and Roof Heat gain through the exterior construction is normally calculated at the time of greatest heat flow. It is caused by solar heat gain being absorbed at the exterior surface and by the temperature between the outdoor and indoor air. Both heat sources are highly variable throughout a day, results in unsteady state heat flow through the exterior construction. It can be evaluated best by means of equivalent temperature difference across the structure.

9 Q = A x U x EqTD Where A = Area of the wall or roof (m or ft 2 ) U = Transmission coefficient in Btu/h/ft 2 /deg F EqTD = corrected equivalent temperature difference in deg F Solar heat gain through glass The heat gain through ordinary glass depends on latitude, time of day, time of year, facing direction of glass. Ordinary glass absorbs a small portion of the solar heat reflects or transmits the rest. The solar heat gain in the conditioned space consist of transmitted heat plus a part of the heat that is absorbed by the glass. Heat gain = A x R x MF Where A = Area of the glass (m 2 or ft 2 ) R = Solar gain in Btu/h/ft 2. MF = Multiplying factor for the type of glass Transmission gain through partitions, ceiling, floor & glass Heat gain by transmission is due to temperature difference on both sides of partition or ceiling or floor or glass. The wall of air-conditioned room, which is not exposed to sun, is referred as ceiling. Heat gain through floor is generally neglected. Heat Gain = A x U x TD Q Where A = area of the partition/ceiling (ft 2 ) U = transmission coefficient in Btu/h/ft 2 /deg F. TD = Temperature difference from surrounding and air Con ditioning space in deg F Infiltration Load Infiltration involves the heat gain or loss to the conditioned space due to the replacement of the conditioned air by the undesirable outside air. Infiltration air quantity is calculated from the infiltration rate. The load includes sensible and latent heat and is evaluated in the same manner as the ventilation load Ventilation Load Ventilation is the introduction of outdoor air in to conditioned space to dilute the body odors given off by the people or other air contaminants. Room load due to fresh air Where Qv = Qv x density x Cp x BF x TD = Quantity of fresh air taken (CFM). Cp = Specific heat of air. TD = Temperature

10 difference between the surrounding and the conditioned space (deg F). BF = Bypass factor. Q = 1.08 x CFM x BF x TD Internal and system heat gain The sensible and latent heat gain due to occupants, lights, appliances, machines, piping, ducts etc with in the conditioned space from the components of the internal and system heat gain Occupancy Load Heat generated within the human body by process of metabolism, the metabolism rate for women is 85% and for children it is 75%. The metabolic rate varies with the type of activity of the individual. Q = No. of persons x heat per person (Btu/hr) Lighting Load Electric lights generates a sensible heat equal to the amount of electric power consumed. Most of the energy is liberated as heat and rest as light, which also becomes heat after multiple reflections. After the wattage is known the calculation of heat gain is done as follows. Fluorescent light Q = Total watts x Incandescent light Q = Total watts. In fluorescent light 25% more energy is liberated at the control gear of the fitting. Often lighting load is calculated based on watts per square feet of floor area Fan and Electric Motors Fan horsepower For calculating this value Brake horsepower of the fan X 641 Brake horsepower of the fan X 2545 kcal /hour Btu/hour Appliances Some appliances give both sensible and latent heats. The latent heat being given off directly or as result of their function such as cooking, drying etc. refer to the data provided by manufacturers of the appliances or the design tables for arriving at the sensible heat contributed by the appliances Safety factor An additional 5% on room sensible heat is taken as safety factor and this also covers items such as heat gain by the supply duct, leak etc.

11 Where, Qda ERSH T room T adp C BF P = Dehumidified air quantity in CFM = Effective room sensible heat in BTU/h = Room design temperature in F = Apparatus dew point temperature in F = Specific heat of air (0.24) = By pass factor of the coil = Density of air (0.075 lbs/ft 3 ) To systematically calculate the cooling load, standard cooling load estimation forms are used. A typically format of the form is given as follows. Heat gain is separated into the room sensible heat, room latent heat, room total heat and grand total heat, to facilitate the calculations for the air quantity required and for equipment selection Determination of Air Quantity (CFM) The air quantity selected should offset the room sensible and latent heat load. It should also handle the total sensible and latent heat loads, i.e. including the outdoor (fresh) air loads, etc. The air quantity can be determined from the formula ERUSH Qda = (T room T adp) X (1 BF) X 60 X X C Therefore air quantity in ERSH CFM = 1.08 X (T room T adp)(1bf) 3.18 DIVERSITY OF COOLING LOADS Diversity of cooling load results from the probable non-occurrence of part of the cooling load on a design day. Diversity factors are applied to the refrigeration capacity in large air conditioning systems. These factors vary with location, type and size of the application and are based entirely on the judgment of the engineer Table Typical diversity factors for large buildings Type application of Diversity Factor People Lights Big offices 0.75 to to 0.85 Apartment, Hotel Department Store 0.40 to to to to 1.0 Industrial 0.85 to to 0.9

12 3.19 COOLING LOAD CALCULATION 1. INDIAN ADMISSION (LOCATED IN THE FIRST FLOOR) Outside design conditions: D.B.T = 104F W.B.T = 81F R.H = 50% Latitude = 12.52N Daily Range = 15F Inside design conditions: D.B.T = 75F R.H = 50% Solar gain Glass: Solar gain heat = A x R x M.F Where, A = Area of glass in ft 2 R = Solar gain in BTU/h/ft 2 From the table 1&2, R = B.T.U/hr-ft 2 M.F = Multiplying factor for the type of glass, shading, etc.. The Multiplying Factor for ordinary glass and inside Venetian blind = HEAT LOAD CALCULATION FOR CONFERENCE HALL South glass Area of the glass Solar gain Heat = 100 ft 2 = A x R x M.F = 100 x x 0.56 = 616 BTU/h West glass Area of the glass Solar gain Heat North glass Area of the glass Solar gain Heat = 176 ft 2 = A x R x M.F = 176 x 155 x 0.56 = 1084 BTU/h. = 250 ft 2 = A x R x M.F = 250 x 50 x 0.56 = 5460 BTU/h Solar and Transmission heat gain Walls and Roof Heat gain = A x U x EqTD Where, A = Area of the wall or roof in ft 2 U =Transmission coefficient of the wall or roof=0.35btu/h/ft 2 /F EqTD = Equivalent temperature Equivalent difference + Correction Factor. = 12F (Temperature difference ) Correction Factor from the Table 6A, At Outside design temperature minus room temperature and Daily range= 6F. Where, outside design temperature minus room temperature = = 29F.

13 North wall Heat gain = A x U x EqTD Where, A = Area of the wall =3390 ft 2 U = Transmission coefficient of the wall=0.35 BTU/h/ft 2 /F. EqTD = Equivalent temperature difference + Correction factor = 18F Heat gain = 3390 x 0.35 x 18 = BTU/h South wall Heat gain = A x U x EqTD Where, A = Area of the wall = 3450 ft 2 U = Transmission coefficient of the wall=0.35 BTU/h/ft 2 /F. EqTD = Equivalent temperature difference + Correction factor = 30F Heat gain = 3450x 0.35 x 30 = BTU/h West wall Heat gain = A x U x EqTD Where, A = Area of the wall = 1560 ft 2 U = Transmission coefficient of the wall = 0.35 BTU/h/ft 2 /F. EqTD = Equivalent temperature difference + Correction factor = 26F Heat gain = 1560 x 0.35 x 26 = BTU/h East wall Heat gain = A x U x EqTD Where, A = Area of the wall = 1484 ft 2 U = Transmission coefficient of the wall = 0.35 BTU/h/ft 2 /F. EqTD = Equivalent temperature difference + Correction factor =F Heat gain = 1484 x 0.35 x 32= BTU/h Transmission gain except walls and roofs Glasses Heat gain = A x U x T.D Where, A = Area of the total glasses = 626 ft 2 U T.D Heat due glasses gain to = Transmission Coefficient for glasses from the = 1.13 BTU/h/ft 2 /F. = Temperature Difference between the Surroundings and the conditioned space = = 29F. = 626 x 1.13 x 29 = BTU/h Partitions: A = Area of the partition walls (not exposed to sun)= ft 2

14 U T.D = Transmission Coefficient for partition walls Temperature Difference measure = (104 75) -5 = 24F. Heat gain = x 0.35 x 24 = BTU/h floor A = Area of the room = ft 2 U T.D Heat gain due to Ceiling = Transmission Coefficient for ceiling from the = 0.39 BTU/h/ft 2 /F. =Temperature Diff. between the surroundings and the conditioned space minus 5F = (104 75) -5 =24F. = 16752x 0.39 x 24 = BTU/h INTERNAL HEAT People Heat gain for people = N x Sp Where, N = Number of people = 30 Sp = Sensible heat per person Heat gain from people from the Table 10 = 255 BTU/h/person = 30 x 255 = 7650 BTU/h Lights Load due to lights is calculated below Fluorescent light 3.4 Considering 1.25 watt/sq.ft, = Total sq,feet x 1.5 x A = Area of the room = 3250 ft 2 Heat gain due to lights = x 1.5 x 3.4 = BTU/h Additional Heat Gains Assume 0 KW Additional Heat load = 0x 1000 x 3.4 = 0 BTU/h Sub total of Room Sensible Heat Adding the values of all sensible loads is giving the Sub total of room sensible heat. R.S.H (sub) = BTU/h Safety Factor 13% subtotal of room sensible heat is taken as a safety factor. S.F = 0.13x = BTU/h Room Sensible Heat Adding the values of e and f is gives the room sensible heat. Room =

15 Sensible Heat = BTU/h System heat gain This system heat gain generally we take 10% of room sensible heat. System Heat gain = 0.1 x Room sensible heat = 0.1 x = BTU/h Heat gain through (by passed) fresh air The room load due to the by passed fresh air (through the cooling coil) is Heat gain in BTU/h = CFM X 1.08 X BF X TD. From the Table 11, for this application CFM/person is = 5. Total CFM = Number of people x CFM/person = 30 x 5 = 150 CFM Coil Bypass Factor from table 12, for this type of application is = 0.12 Where TD = Temperature Difference between the surroundings and the conditioned space = = 29F Heat gain = 150 x 1.08 x 0.12 x 29 = BTU/h Effective Room Sensible Heat It is obtained by adding up the items g, h and i. Effective Sensible Heat Room = BTU/h Latent heat People Heat gain from people = N x Lp Where, N = Number of people = 30 Lp = Latent heat per person from the table 10 Heat gain from people = 205 BTU/h/person = 300x 205 = 6150 BTU/h Appliances No moisture is generated in this room Subtotal of room latent heat Adding the values of k.1 + k.2 + k.3, we get the sub total of room latent heat. Subtotal of room latent heat = 6150 BTU/h Safety Factor An addition of 5% on subtotal of room sensible heat is taken as a safety factor. S.F = 0.05 x 6150 = BTU/h.

16 Room Latent Heat Adding the values of l and m is gives the room sensible heat. Room Sensible Heat = = BTU/h Supply Duct Leakage loss Supply duct leak loss = CFM x BF x Gr/Lb x 0.68 = 6365 BTU/h Effective Room Latent Heat It is obtained by adding up the items n, o and p. Effective Latent Heat Room = BTU/h Effective Room Total Heat It is the sum of effective room sensible heat and effective room latent heat. Effective Room Total Heat = BTU/h Outdoor air Heat Sensible heat: Outdoor air Sensible heat = 1.08 X CFM X (1 - BF) X TD = 1.08 X 150 X (1 0.12) X 29 = BTU/h Latent heat Outdoor air = 0.68 X CFM X Latent heat TOTAL HEAT Outdoor air Total Heat (1- BF) X (Wo Wi) = 0.68 X 150 X (1 0.12) X (58) = BTU/h. = BTU/h Sub Total of grand total heat Adding the values of effective room total heat and outdoor air total heat, we get the sub total of grand total heat. G.T.H (sub) = BTU/h Percent addition to grand total heat The percent additions to the grand total heat to compensate for various external losses consist of Percent Return air heat gain, return air leak gain: Generally ignored Fan H.P: Draw through system, so ignored. Dehumidifier and piping losses: 3 % added the sub total of G.T.H The G.T.H addition = 0.03 x = BTU/h GRAND TOTAL HEAT Adding the values of items t and u, we get the grand total heat.

17 Grand Total Heat = BTU/h = /12000 = T.R Determination of Air Quantity (CFM) The air quantity in adp) (1 BF) CFM = ERSH 1.08 X (T rm T Effective Room Sensible Heat Factor: It is the ratio of Effective Room Sensible Heat to Effective Room Total Heat ERSHF = 0.99 Indicated A.D.P (T adp) = CHAPTER-IV RESULTS AND DISCUSSION 54 F 4.1 HEAT LOAD CALCULATION Heat load from the various materials and appliances are calculated by using the heat load spread sheet and the values which are calculated are tabulated below. 4.2 DUCT DESIGN Duct design and size calculation are made by using duct seizer software it is an electronic duct calculator for sizing duct and calculating pressure drops, as per the CFM the size of the duct is calculated in this we have designed for the rectangular duct. 4.4 CONCLUSION Heat load calculation and Duct design are made successfully as per the requirement, air cooled AHU are used here for the cooling purpose. CHAPTER - V CONCLUSION After receiving job order from the client the drawings and the documents were transferred from sales to erection team. The various drawings related to job were finalized with consulting the client. Subsequently the order for various equipment s was placed. The piping and ducting work was started first. By the time ducting and piping work was completed, the main equipment received at the site, then the air handling units were installed. All pipes were covered with insulation material. Then a false ceiling with thermo Cole pad was erected in various floors. The ducts were fabricated at the site according to the dimensions of drawings were erected from air handling units to the area to be conditioned. Grills were installed at duct openings. The ducts were covered with thermal or acoustic insulation according to design drawings. The air handling units were installed in AHU rooms. The AHU fan pulley was

18 connected with the motor pulley. The plant room flooring was done in such a way that in can absorb all vibrations coming from compressors. After finishing the installation and erection of every equipment, pre commissioning of the plant was done. That is every equipment was tested whether it can do the required job or not. The refrigerant is charged into the system by connecting the cylinder in the suction line and running the compressor until whole refrigerant lines were filled with charge. Then the plant was commissioned and the required conditions were achieved by existing various controls. Once the required conditions were stabilized the plant was handed over to the client. REFERENCES: 1)Fiorentini M, Cooper P, Ma Z, Sohel MI. Implementation of a solar PVT assisted HVAC system with PCM energy storage on a netzero energy retrofitted house. Asia-Pacific Solar Research Conference, Sydney, Australia, 8-10 Dec ) West SR, Ward JK, Wall J. Trial results from a model predictive control and optimisation system for commercial building HVAC. 3)Afram A, Janabi-Sharifi F. Theory and applications of HVAC control systems A review of model predictive control (MPC).Building and Environment. 2014;72(0): )Fiorentini M, Cooper P, Ma Z. Development and Optimization of an Innovative HVAC System with Integrated PVT and PCM Thermal Storage for a Net-Zero Energy Retrofitted House. Accepted for publication by Energy and Buildings. February ) Ren MJ, Wright JA. Adaptive Diurnal Prediction of Ambient Dry-Bulb Temperature and Solar Radiation. HVAC&R Research. 2002;8(4).