DEVELOPMENT OF A COMPUTER PROGRAM TO OPTIMIZE AN AIR CONDITIONING SYSTEM FOR LOCAL UTILIZATION

FRANK MURPHY ANAK JUNAIDI KUTOI

This project is submitted in partial fulfilment of the requirements for the degree of Bachelor of Engineering with Honours

(Mechanical Engineering and Manufacturing Systems)

Faculty of Engineering UNIVERSITI MALAYSIA SARAWAK

2004

Dedicated to My Beloved Family

May God Bless All of You, Always

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ACKNOWLEDGEMENTS

The author would like to express his grateful thanks to his supervisor En.

Rash Muslimen for his guidance, patience and support, which have helped a lot in

making this project to be completed. Many thanks are also given to the staffs of

maintenance especially the air conditioning department and CAIS, UNIMAS for

their generous assistance and cooperation, and other supporting individuals

especially to his colleagues and friends. Finally, the author would like to thank his

family for their supports.

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ABSTRACT

This project is regarding the development of a computer program in which it aims to

optimise the air conditioning system in the local area. Before the development

process of the program, various conditions that can influence the optimising process

of the air conditioning system must be identified. These review includes the

problems' background, calculate the heat gain and to optimise the energy usage.

Experimental and research methods are used to achieved this purpose, which is to

gather necessary data. Once the program is successfully developed it should been

able to calculate the heat gain of the building. Thus it can optimise the energy usage

for the air conditioning system. One building has been selected as the model to test

the program and the result will also be reviewed for the future references. For this

project the Centre for Academic Information Services (CAIS) building in UNIMAS

will be taken as the energy analyses model. From the analyses it is found that the

total energy that can be optimised is up to 11.36 % of cooling load. From the study

also several recommendations has been stated in order to save or to optimise the

energy in the building.

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ABSTRAK

Projek ini adalah berkenaan dengan pembangunan satu program komputer di mana ia

bertujuan untuk mengoptimiskan sistem penghawa dingin udara di kawasan

tempatan. Sebelum proses pembangunan program ini, pelbagai keadaan yang boleh

mempengaruhi proses pengoptimisan sistem penghawa dingin udara mestilah

dikenalpasti. Ini termasuklah latarbelakang masalah, penghitungan haba yang

diterima dan pengoptimisan tenaga yang digunakan. Kaedah eksperimen dan

penyelidikan telah digunakan untuk tujuan tersebut iaitu pengumpulan data yang

berkenaan. Apabila program ini telah berjaya dibangunkan, ia sepatutnya boleh

mengira haba yang diterima pada sesuatu bangunan. Oleh itu, pengoptimisan tenaga

bagi sistem penghawa dingin udara akan dicapai. Satu bangunan akan dipilih sebagai

model untuk tujuan percubaan program dan keputusan yang diperolehi akan

dibincangkan untuk tujuan penyelidikan masa hadapan. Untuk projek ini, bangunan

Pusat Khidmat Maklumat Akademik (CAIS) di UNIMAS akan dijadikan 'sebagai

model untuk analisis tenaga. Daripada analisis tersebut, didapati sehingga 11.36 %

tenaga untuk beban penyejukan boleh di optimiskan. Berdasarkan kajian itu juga,

beberapa langkah telah dinyatakan untuk menjimat atau untuk mengoptirniskan

tenaga di bangunan berkenaan.

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TABLE OF CONTENTS

DEDICATION

ACKNOWLEDGEMENTS

ABSTRACT

ABSTRAK

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

1. INTRODUCTION

1.1 Introduction

1.2 Objectives

1.3 Scope

1.4 Problems Statement

1.4.1 Background of the problems

1.4.2 To calculate the heat gain

1.4.3 To optimize the usage of the energy

1.4.4 The development process of the program

2. LITERATURE REVIEW

2.1 Basic Principle of the Air Conditioning

2.2 Air Conditioning in the World

2.2.1 The World Market

2.2.2 Annual Expenditure for Air Conditioning

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2.2.3 Equipment Rate of Air Conditioning

2.3 Heat Loss and the Heat Gain in the Building

2.3.1 Heat lost from the building

2.3.2 Previous Studies Done

2.4 Psychrometric Chart

2.5 Method of Refrigeration

2.5.1 Compression System

2.5.2 Absorption System

2.6 Design Procedure for Air Conditioning

3. METHODOLOGY

3.1 Gathering Data

3.2 Experimental Procedures

4. RESULTS AND DISCUSSIONS

4.1 Main CAtS

4.2 Discussion Room

4.3 Office Area 1

4.4 Office Area 2

4.5 Office Area 3

4.6 Photocopy Centre

4.7 Computer Laboratory

4.8 Journal Collection Room

4.9 Thesis Collection Room

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5. CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions

5.2 Recommendations

5.2.1 Improved Computer Program Analysis

5.2.2 Improved Design

5.2.3 Improved Operations

5.2.4 Other Design Considerations

REFERENCES

APPENDICES

APPENDIX I

APPENDIX 2

APPENDIX 3

APPENDIX 4

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VIII

LIST OF TABLES

Table 2.1

Table 2.2

Table 3.1

Table 4.1

Table 4.2

Table 4.3

Table 4.4

Table 4.5

Table 4.6

Table 4.7

Table 4.8

Table 4.9

Table 4.10

Equipment rate of air-conditioning in the world in 1997

Shows Common Used Refrigerant in the Industry

Manual Work Analysis

Cooling Load Analysis for Main CAIS

Cooling Load Analysis for Discussion Room

Cooling Load Analysis for Office Area I

Cooling Load Analysis for Office Area 2

Cooling Load Analysis for Office Area 3

Cooling Load Analysis for Photocopy Center

Cooling Load Analysis for Computer Laboratory

Cooling Load Analysis for Journal Collection Room

Cooling Load Analysis for Thesis Collection Room

Comparison of Total Cooling Load for CAIS Building

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LIST OF FIGURES

Figure 2.1 The figure indicate the refrigeration cycle

Figure 2.2 Air-conditioner world market (in volume) in 2000

Figure 2.3 Annual expenditure for air-conditioning in 2000

Figure 2.4 Evolution from 1971 to 2001 of World Electricity

Generation by Region (TWh)*

Figure 2.5 1973 and 2001 Regional Shares of Electricity

Generation*

Figure 2.6 Indicates the sources of air leaks in the building

Figure 2.7 The Psychrometric chart

Figure 3.1 Step 1: Roof and Ceiling Properties

Figure 3.2 Step 2: Windows Properties

Figure 3.3 Step 3: Doors Properties

Figure 3.4 Step 4: Walls Properties

Figure 3.5 Final Step: Estimated Cooling Load

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CHAPTER I

INTRODUCTION

1.1 Introduction

This project is regarding the development of a computer program in which

has the functions to analyse and calculate the heat gain of the building. By

calculating the heat gains, a suitable cooling load will be suggested in order to

optimise the energy usage air conditioning system. Each air conditioning system for

each particular room in the building will be optimised, so that no excess cooling load

will be allowed.

1.2 Objectives

This project is regarding the development of a program that has two

functions, which are capable:

i) To calculate the sensible heat gains

ii) To optimise the use of energy for air conditioning.

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Every year, the expenditure for the energy consumption is increasing and it is

expected that it will continuously increasing. One of the purposes for the energy

used is to generate the air conditioning system. Since every room in the building has

its own air conditioning unit, it is appropriate to optimise the usage of the energy for

the air conditioning purposes. Using this program, the selection of the proper air

conditioning unit or system will be taken consideration.

Although there are several programs that are similar available in the market,

the development of this program is essential since it will become the first step to

development process of a tool that can estimate or select the appropriate air

conditioning unit for the local utilization. Most of the programs or software available

in the market are developed by the western companies, which have different weather

condition.

1.3 Scope

This project is concern about the study about the air conditioning system in

UNIMAS. For this purpose, all the data needed for this project will be recorded and

will be conducted at UNIMAS.

In this project, there are three known phases that have to he investigated. The

first phase is information-gathering process. Using the methods mentioned in the

next chapter, all related information regarding the air conditioning system would be

collected. The second phase is where the experiment will he conducted. After

obtained the results, a computer program will be developed using a selected

programming language. Finally, the final phase will be conducted. It is where the

computer program will be tested in a selected building in the UNIMAS. For this

purpose, one building will be selected as the model, which is the Centre for

Academic Information Services (CAIS) building since the usage of the air

conditioning can be considered as the most stable.

1.4 Problems Statement

1.4.1 Background of the problems

There are few problems that have been identified, which are related to the

topic. Each problems must been taken seriously in order the purposes of the topics is

achieved. To simplify the problems, all the problems can be categorized into three

main categories, which are:

i) To calculate the heat gain and heat loss

ii) To optimise the usage of the energy

iii) The development process of the program

After these problems have been simplified, appropriate measurements can be

taken in order to tackle it efficiently.

1.4.2 To calculate the heat gain

Before the heat gain of the building can be calculated, the factors that can

affect these load must been initially determined. One of the factors that can affect

these loads is the weather condition, which includes the external temperature and the

air humidity. Although, the weather condition is varies across the time, but we still

can assume that the temperature and the air humidity will not vary much.

The second factor that can greatly affect the calculation of the loads is the

materials selection of the building. Since different materials have its own

characteristics, so different level of heats will been allowed to be transferred by the

materials. One of the factor that influence the number of heat to been transferred

through the materials is the thermal transmittance, which will be further discussed in

the next topic.

Another factor that can not been ignored during the determining process of

the factor, which can affect the heat gain and loss is the design of the building and its

orientation. Let it bear in mind that the building will absorb more heat in the evening

compared in the morning. So, the larger of the surface area of the building facing the

west, it can be concluded that the more exposed of the building to the solar radiation.

For an example, the building which was facing the east-west direction is tend to

absorb more heat than the building that facing north-south direction. Another factor,

which is not least important, is the shading and the awning of the building. The term

shading in this context is referred to the area of the building being covered by

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another object in which blocked the direct solar radiation. This blocked solar

radiation will reduce the chances of the absorbent of the heat by the building.

In order to calculate the heat gain and heat loss of the building, another factor

that cannot be left out is the internal "heat producers". These internal heat producers

can be referred to the objects inside the building, which can produce some amounts

of heat, such as machines, human, computers and the lighting system. In the past,

this factor is often being opt-out since there are no sophisticated equipments that can

calculate the amount of heat produced.

1.4.3 To optimise the usage of the energy

Before start selecting the air conditioning unit or system, one must now

consider how to select appropriate unit in order to optimise the usage of the energy.

From the previous researches done by the experts, this problem was their main issue

due to the increasing of the energy usage by the air conditioning system around the

world. The system must be selected based on their cooling loads and efficiencies.

Excess cooling loads means more energy will be wasted while less loads means less

efficient the system would be.

For further discussion about how to optimise the usage of' the energy, the

details will be discussed in the next topics.

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1.4.4 The development process of the program

Before start developing the program, one must carefully design the flow of

the program using the flow control chart. During the process, all the formulas needed

must been selected according to function need. The formulas selected then will be

used to calculate the heat gain and heat loss and to calculate the cooling loads of the

air conditioning unit. Related to the formulas, one also must determine what types of

information needed to be collected since this data will be used in the program

calculation. To prevent any redundancy in the programme coding, only appropriate

data and formulas will be considered.

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CHAPTER 2

LITERATURE REVIEWS

2.1 The Basic Principles of the Air Conditioning

Air conditioning can be defined as the process of treating air so as to control

simultaneously its temperature, humidity, cleanness and distribution to meet the

requirements of the conditioned space. As indicated, air conditioning is much more

than only cooling the space where people are living or working in. One important

teen that needs to be considered here is the comfort factor, which is the condition

where the occupants are fell well-being to the surrounding environment. Since the

purpose of the air conditioning is to ensure comfort to occupants, it is difficult to

determine exact condition that can satisfy every people. For this reason, the comfort

condition used in this analysis is assumed to be 73 to 79 F at 68 F WB and 74 to 81 F

at 36 F DP, and the humidity of 50% ''(11. This zone is based on the ASHRAE

Standard 55.

The basic function of an air conditioning system is to supply treated air

throughout a building at the rate and condition required to counteract heat and

moisture gains and losses (loads) so that temperature and humidity are maintained

within acceptable limits.

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An air conditioner works similar to a refrigerator since both of them using the

same principles. The refrigerant flows through the system, and changes in state or

condition. There are four processes in the 'refrigeration cycle' III, which can he

referred to Figure 2.1. The compressor, which pumps the refrigerant around the

system, is the heart of the air conditioner. Before the compressor, the refrigerant is

gas at low pressure. Because of the compressor, the gas becomes high pressure and

flows towards the condenser.

At the condenser, the high-pressure gas becomes high-pressure liquid

refrigerant and the heat is discharged. Afterwards, the refrigerant comes into the

expansion valve and becomes low pressure liquid. The low-pressure refrigerant

flows to the evaporator where the heat is absorbed. The low-pressure gas flows to the

compressor where the cycle starts all over again.

The direction of the cycle ------

t ý ý ý

1w

I '" Wlll I, I

IMRlill[DL  1 I11111111! Iiý 'I IIH i [in  

. ý.. , t*n-

Air in

Compressor

i ý

- 4 IE

Figure 2.1 The figure indicate the refrigeration cycle

i

Evaporator

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2.2 Air-conditioning in the world

2.2.1 The World Market

The Air-conditioner world market in the year 2000 can be referred to Figure

2.2. In the year 2000 121, the sales of the air conditioner have been estimated about

39.7 millions of unit around the world market and it is still expanding. The American

market is the biggest with 13.2 millions of units sold in the year 2000 and a growth

rate of 3.1 %. The Chinese market suddenly increases with 9.2 millions of units while

the Japanese market growth adds up to 9% between 1999 and 2000, reaching 7.7

millions of units. In the year 2000, the world market has been assessed

approximately to US$ 35 billions.

Figure 2.2 Air-conditioner world market (in volume) in 2000 121

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2.2.2 Annual Expenditure for Air Conditioning

The chart in Figure 2.3 indicates the annual expenditure for air-

conditioning in the year 2000 for three main countries, which comprises Japan,

USA and the Europe countries. From the chart, Japan lead the other countries with

the expenditure of 71 ¬/ Hab while USA and the countries of Europe are 36 ¬/

Hab and 12 ¬/ Hab respectively. The unit Hab used here referred to the term

habitant. From here we know that all of these countries have spent lots of money

for their air conditioning system expenditures.

Figure 2.3 Annual expenditure for air-conditioning in 2000 I2I

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Figure 2.4 and Figure 2.5 are the charts, which indicate the amounts

electricity, generated in the world in general. From the charts, we notice that the

amounts of electricity needed, which was recorded in the unit of Tetra Watt per hour,

is proportionally with times.

QI Iý QFanl, ll, I. rý Q I"iiini llti`, I: Q tLýi l'II liu, l� Q 'huia ®

""". i. ý U I, dm '"m rn. i Q

""lir. i

Figure 2.4 Evolution from 1971 to 2001 of World Electricity Generation* by Region (TWh) 131

i

6117 TWIT

* Facludcs pumped storage

10 1 -', i

1§ 4 76 TWh 01

** Asia excludes ('hina

Figure 2.5 1973 and 2001 Regional Shares of Electricity Generation* I 'I

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2.2.3 Equipment rate of Air conditioning

The using of room air conditioners type is more widespread especially in

the tertiary sector. The equipment rate in Europe is very low compared to the

other countries of OECD (which stands for Organisation for Economic Co-

operation and Development). From the Table 2.1 Japan is using room air

conditioners type in all of its tertiary building compared to other countries while

USA is in the second place with 80%.

COUNTRY TERTIARY * RESIDENTIAL

Japan 100% 85%

USA 80% 65%

Europe 27% 5%

* Refers to the commercial buildings such as office buildings.

Table 2.1 Equipment rate of air-conditioning in the world in 1997 [2]

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2.3 Heat loss and the heat gain in the building

2.3.1 Heat lost from the building

There are two categories of heat losses from the building 14], which are:

i) The fabric loss

ii) The ventilation loss

The fabric loss

The fabric loss can be defined as the losses of the heat from the fabric

surfaces such as the walls, roof, floors and other types of elements such as the

thermal resistance of the inside and outside surfaces of the building. This loss is

depends on these elements due to the convection through the fluid film on the

surface and thermal radiation from the surfaces to the surrounding.

The overall heat transfer coefficient for the fabric loss, or also known as the

thermal transmittance, U is giver. by the following equation ["]:

II1 -+

ZRý, "+- U h; h,,

Where:

2.1

Heat transfer coefficient, h; and ho, which include both convection

and radiation effects.

>R� ", the summation of the thermal resistance of the elements making

up the wall, roof, etc.

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The thermal transmittance is sometimes known as the U-value of the

building, which is important in the designing process of the building. From the

equation above, the thermal transmittance is much depends on the outside weather

condition since h� value is much varies with the air speed.

Environmental temperatures are defined as the equivalent temperatures

introduced to allow for radiation effects. These temperature can either externally

from solar radiation on the outside surfaces or internally from radiant interchange

between internal surfaces. The outside external temperature, teO is normally been

ignored and taken to be equal to the mean outside air temperature, tao 141

teo - tao ..................................... 2.2

The inside environmental temperature is depends on a few factors such as the

temperatures of the emissivities of the various room surfaces, shape of the room and

the convective heat transfer coefficients for various inside surfaces.

Ventilation loss

The building can either be naturally ventilated by the air movement through

windows, doors and ventilators or mechanically ventilated such as fans, or air

conditioned by providing air through ducts at controlled conditions. So, the

ventilation loss can be defined as the heat loss due to the air leakage to and from the

building through fortuitous cracks, inadequate sealing, etc. the process of leakage is

also known as infiltration. .

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