15-10-2016, 03:30 PM
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Abstract
The development of renewable energy is on the rise worldwide because of the growing demand on energy, high oil
prices, and concerns of environmental impacts. In recent years, progress on solar-powered air conditioning has
increased as nowadays, air conditioning system is almost a must in every building if we want to have a good indoor
comfort inside the building. Therefore, this paper focuses in the design and construction of a direct current (DC) air
conditioning system integrated with photovoltaic (PV) system which consists of PV panels, solar charger, inverter
and batteries. The air conditioning system can be operated on solar and can be used in non-electrified areas. As we
all known, solar energy is cost effective, renewable and environmentally friendly.
Introduction
The demand of air conditioning is increasing due to the effect of climate change and global warming.
If we still rely on the conventional electric air conditioning but electricity is generated form fossil fuels,
the greenhouse gas emission would continuously worsen global warming, in turn the demand of air
conditioning would be further increasing. In subtropical cities, air conditioning is a standard provision
for buildings. However, air conditioning would commonly take up half of building electricity
consumption
Air conditioning is defined as the simultaneous processing of temperature, humidity, purification and
distribution of air current in compliance with the requirement of space needing air conditioning [2]. In
general, air conditioning which also can be known as refrigeration is defined as any process of heat
removal. To produce the process, it requires energy where the sources are commonly gas and electricity.
With increasing gas and electricity tariffs, solar energy becomes attractive once the system has been
installed [3]. As one of the sources of renewable energy, solar energy is likely the most suitable system
for installation in sub-tropical countries.
The most common globally, preferred type of thermally driven technology is absorption cooling. The
system, which has simpler capacity control, mechanism, easier implementation, high reliability, silent
operation, long life and low maintenance cost was a genuine candidate for efficient and economic use of
solar energy for cooling applications [3]. But in this project concentrates on development and
improvement of a normal air conditioner unit in order to operate using electricity generated from the PV
system.
Utilizing solar energy to run the air conditioning system is a practical technique to replace
conventional electricity. In order to obtain a feasibility of the air conditioning system using solar, a lot
research and testing have been initiated to learn and discover the design and operation of the air
conditioning and solar system which is consist of PV system.
The purpose of this paper is to design and construct a direct current air conditioning system besides
describe the component and characteristics of the system including its advantages and limitations. The
actual performance of the system will be studied based on operational view and commercial applications.
2. Methodology
The approaches used in this project are based on suggestion by Tsoutsos et al [4], and are as follows:
a) Collection of the required meteorological data: meteorological data for Perlis was used. A typical
meteorological year (TMY) was created and the hourly, monthly and annual values of solar radiation
processed.
b) Cooling load calculation: Determine what kind of cooling and how much of cooling needed.
c) Design and sizing of the air conditioning system: Using the weather data, and the selected design
conditions, the components of the system could be sized.
d) Optimisation of the system: The aim was to use least cost energy so the designed system was
optimised with that in mind.
e) Material procurement and construction of the experimental system: Once the system had been
optimised, the components were procured and the system was constructed and tested.
f) Performance evaluation and economic analysis: The energetic and economical effectiveness of the
system was evaluated. The life cycle costs for solar cooling system were calculated and
competitiveness with regards to price and thermal efficiency for domestic applications determined.
g) Analysis of results and making of recommendations: The results were analysed and necessary
improvements recommended. Options for improving technical effectiveness and economic
competitiveness were suggested. Ways of improving research and development efforts in this field
were also investigated.
. System Description
The proposed concept of the system consists of air conditioner and PV system is indicated in block
diagram shown in Figure 1. In order to determine the characteristics and properties of all the components
used, each component must be taken as a single unit.
The complete system must be able to operate in stable condition, and if possible achieving the
efficiency as conventional air conditioning system. For example, as for the cooling purpose, performance
of the DC air conditioning should be the same as normal AC air conditioner.
Refrigeration Load
Heat naturally flows from warmer places to cooler places. In other words, the heat is called as
refrigeration load. Refrigeration equipment such as air conditioner is used to transfer heat from a cooler
place to a warmer place. For example, the heat inside a house is absorbed and been transferred to the
outside [4].
The refrigeration load is the rate at which heat must be removed from the refrigerated space in order
to produce and maintain the desired temperature conditions. The total cooling load on the refrigerating
equipment is the sum of heat-gain from several different sources which include the heat gained from
walls, windows and doors [5].