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European Journal of Applied Sciences – Vol. 10, No. 1
Publication Date: February 25, 2022
DOI:10.14738/aivp.101.11644. Ogborwoji, E. E., & Saturday, E. G. (2022). Estimation of Air Conditioning Load for a Lecture Auditorium. European Journal of Applied
Sciences, 10(1). 463-475.
Services for Science and Education – United Kingdom
Estimation of Air Conditioning Load for a Lecture Auditorium
E. E. Ogborwoji
Mechanical Engineering Department
University of Port-Harcourt, Nigeria
E. G. Saturday
Mechanical Engineering Department
University of Port-Harcourt, Nigeria
ABSTRACT
The estimation of air conditioning load for a lecture auditorium in the Department
of Mechanical Engineering, University of Port Harcourt was carried out in this work.
The auditorium is at latitude 4.9069°N and longitude 6.9170°E. The grand total heat
load of the auditorium was estimated with the use of MATLAB software. The grand
total heat load was estimated to pave the way for the installation of appropriate air
conditioning units. Parametric analysis was also carried out to determine the effect
of different parameters on the grand total heat load. The results showed that an
increase in the outdoor temperature and number of glass windows in the building
will lead to an increase in the grand total heat load posed on the building if other
variable physical parameters are kept constant, while an increase in the indoor
temperature of the building will lead to a decrease in the grand total heat load of
the building when other variable physical parameters are kept constant. The
methodology used in the air conditioning load estimation for this case study can be
easily applied to other buildings. The work will be useful to air conditioning
engineers, individuals and groups who intend to install air conditioning systems in
homes and auditoriums.
Key words: Load estimation, Parametric analysis, MATLAB, Grand total heat.
INTRODUCTION
Air-conditioning involves maintaining a given space at a predetermined temperature and
relative humidity by supplying clean and conditioned air to the given space for human comfort
and / or product processing [1]. This treatment or control of the air deals basically with the
temperature and humidity of the air and has become very important to man because of the
harsh climate conditions and seasonal changes in the world. The cooling of the supply air
follows basic refrigeration techniques using refrigerants. some of the refrigerants used has
ozone layer depletion potentials and has been of concern [2] Issues concerning the use of
different refrigerants as well as the performance of a number of refrigerants have been
sufficiently studied [3-6]. There are thus several works aimed at exploiting thermoelectric
cooling instead of refrigerant-based cooling systems [7-10].
Air-conditioning may involve either increasing or decreasing the temperature of the
conditioned space. Cosnier et al. [7] presented an experimental and numerical study of a
thermoelectric air-cooling and air-heating system. They have reached a cooling power of 50W
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European Journal of Applied Sciences (EJAS) Vol. 10, Issue 1, February-2022
Services for Science and Education – United Kingdom
per module, with a COP between 1.5 and 2, by supplying an electrical intensity of 4A and
maintaining the 5°C temperature difference between the hot and cold sides. Shen et al. [11]
investigated a novel thermo-electric radiant air-conditioning system (TERAC). The system
employs thermoelectric modules as radiant panels for indoor cooling, as well as for space
heating by easily reversing the input current. Based on the analysis of a commercial
thermoelectric module they have obtained a maximum cooling COP of 1.77 when applying an
electric current of 1.2A and maintaining cold side temperature at 20°C.
Manoj et al [12] presented an experimental study of novel potential green refrigeration and air- conditioning technology. They analyzed the cause and effects of an existing air-conditioning
system. Thermoelectric cooling provides a promising alternative refrigeration and air
conditioning technology due to their distinct advantages. The available literature shows that
thermoelectric cooling systems are generally only around 5-15% as efficient compared to 40-
60% achieved by the conventional compression cooling system. The problem of global warming
and emission of harmful gases due to use of refrigerants like Freon and Ammonia can be
prevented by using thermoelectric modules air conditioner [13]. How right sizing of equipment
helps to meet the accurate prediction of the cooling or heating loads was explained by Kumari
et al [14]. Right-sizing of heating, ventilation and air conditioning (HVAC) system aids the
selection of equipment and the design of the air distribution system to meet the accurate
predicted heating and cooling loads of the house. Bharathi et al [15] analyzed the cooling load
calculations, design calculations involved in selection of air conditioning systems. The sizing of
an air conditioning system and how to find out the most appropriate temperature required for
the selected room in which we put the AC was the subject of discussion by Raj and Soni [16].
Energy source for powering air-conditioning systems have been an issue as electricity from
fossil fuels has been majorly used in powering air-conditioning systems. The use of solar energy
for powering air-conditioning systems has been the focus in recent studies [17.18].
In Nigeria, the weather condition is mostly very hot, resulting from the intensity of solar
radiation on this part of the world and makes the need for cooling a pertinent one in the country.
Most universities in the country built structures without proper ventilation and airing systems,
hence students are made to digest complex topics in the lecture hall amidst thermal
inconveniences. The need for a cooling system in one of the lecture auditoriums in the
department of Mechanical Engineering, University of Port Harcourt inspired this work. The
auditorium is at latitude 4.9069°N and longitude 6.9170°E. The cooling load of the auditorium
was estimated in this work so as to pave way for the selection and installation of appropriate
air-conditioning units. The analysis could easily be applied to other lecture theaters by merely
varying relevant input data.
MATERIALS AND METHODS
System description
The air conditioner in a building is a cooling system that provides cool air via a process that
draws out the warm air inside, removes its heat and replaces it with a cooler air. The
Mechatronic Engineering building is located at a latitude of 4.9069°N and longitude 6.9170°E.
Having both offices and auditorium compartments, it was erected in an open space where the
sun can incident it from different angles and directions. The auditorium has a seating capacity
of about 500 persons.
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Ogborwoji, E. E., & Saturday, E. G. (2022). Estimation of Air Conditioning Load for a Lecture Auditorium. European Journal of Applied Sciences,
10(1). 463-475.
URL: http://dx.doi.org/10.14738/aivp.101.11644
Design Conditions of Air Conditioning Systems
Before proceeding with an air conditioning design; the inside and outside conditions have to be
specified. Also, the supply air condition has to be fixed.
Indoor Design Conditions
The choice of inside air conditions depends on the application. In this case it’s a comfort air
conditioning. Parameters for measuring comfort include: air temperature, relative humidity, air
velocity, air purity, pressure differential between the space and surroundings. However, a
parameter called the effective temperature is used to correlate the combined effects of air
velocity, air purity, air temperature and relative humidity. In high occupancy applications, it
may be economical and still comfortable to specify the summer indoor relative humidity as 55
to 60 percent. Table 1 shows the indoor design conditions, although parametric analysis was
carried out.
Outdoor Design Conditions
Outdoor design conditions (temperature, humidity, wind conditions, solar radiations) are
highly variable, both by season and by time of day. Table 2 shows the outdoor design conditions.
Table 1: Indoor design conditions
Design Parameters Values
Effective temperature 22 °C
Dry bulb temperature 22±1 °C
Relative humidity 60±5 %
Table 2: Outdoor design conditions
Design Parameter Values [°C]
Maximum dry bulb temperature
(���!"#)
Minimum dry bulb temperature
(���!$%)
Change in dry bulb temperature ∆���&
35
22
13
Wet bulb temperature 24
Cooling Load Calculations
The major components of cooling loads in buildings are due to solar radiation, transmission
through the building fabric or structure and fresh air for ventilation. However, in design
applications for theatres and auditoriums, the predominant cooling load is due to occupancy.
The components of cooling load are classified into four (4) categories. They are external cooling
load, cooling load due to infiltration and ventilation, internal (room) cooling load and system
cooling load. Each of these is presented below.
External Cooling Load
The external cooling load is to a large extent, a product of the fabric heat gains such as heat
gains from the walls, roof, partitions, windows, ceiling and floor. However, the exteriors
(windows) of the mechatronic engineering building in the University of Port Harcourt (used as