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Ma. Fernanda Pitalua Venegas A01410294
Emily Yulin Llera Chi A00513
INSTITUTO TECNOLÓGICO DE ESTUDIOS SUPERIORES DE MONTERREY
In the following work we will analyze the simple cooling system of an air
conditioner, which is composed of a condenser, a compressor, an evaporator
and a valve. The main objective of this paper is to apply the knowledge acquired
in class to perform a mathematical analysis of a refrigeration system which
belongs to a domestic air conditioner. Depending on the technical specifications
of the product we will proceed to make the necessary calculations to obtain the
system’s Coefficient of Refrigeration and the exit Heat.
The use of refrigeration has proved to be of fundamental importance in food
preservation. It is, from the energy point of view, one of the most economical
methods of conservation; therefore we can't be without it. In addition, ambient
air conditioning has become very common and in many cases essential, not
only to achieve comfortable thermal conditions, but also to maintain an indoor
air quality acceptable to the occupants.
Modern society bases its way of life on an intensive consumption of energy, is
essential in almost all our daily tasks, and refrigeration, including air
conditioning, is a sector that has an important participation in this consumption.
A refrigerating machine is based on the physical property that the evaporation of
a liquid or the expansion of a gas absorbs heat, and the compression or
condensation give off heat. This machine applies the so-called cooling cycle.
This cycle obeys the law of perfect gases and the pressure-temperature
P·V = R·m·T; where P is pressure, V is Volume, m is mass in kilos, R is the
universal constant of gases and T is temperature
In order to circulate the refrigerant and optimize its absorption of heat a
compressor is used. The compressor absorbs the refrigerant as a gas at low
pressure and low temperature and moves it compressing it towards the high-
pressure area, where the refrigerant is a gas at high pressure and high
When passing through the condenser the heat of the refrigerant dissipates to
the environment. The refrigerant liquefies and continues under high pressure.
From there, it passes through the pressure regulating device which separates
the areas of high pressure and low pressure by a reduction of the passage
section. As the pressure drops, the refrigerant saturation temperature drops,
allowing it to absorb heat. Already on the low-pressure side, the refrigerant
reaches the evaporator where it absorbs the heat from the environment and
evaporates. From there it goes back to the compressor closing the cycle.
Due to the constant presence of refrigerating machines it was decided to take
one as an example to analyze, to better understand its operation and to be able
to apply the subjects seen in class.
The product that is analyzed is a domestic air conditioning brand Whirlpool
model WB230AB (air conditioning split 3500 FC). The product data sheet is
Refrigerant Rate (Qin) = 3.5 KJ/s
Power (Wnet) = 1.090 KJ/s
Maximum circulation of air (Ċ) = 620 m3/h = 0.1722 m3/s
The refrigerant with which the equipment works is R410A, which is an ecological gas, since it does not attack the ozone layer. It is an almost azeotropic gas mixture, that means that in the liquid phase is a homogeneous gas, but in the gas phase, does not maintain a uniform mixture. It has a working pressure 1.6 times higher than the R22 refrigerant and also a specific compressed oil, Polyol Ester, which is different from R22, with a high degree of hygroscopicity, requiring special care of not to leave residues of moisture in the system.
Mass of the refrigerant that enters the equipment = 0.020 kg