Refrigeration Essay

CHAPTER - 1

INTRODUCTION

1.1. GENERAL

In present day, as population increases the need also increases. The human being needs more comfortness because of inferior environment (like light, sound, machine which produce heat). Sound, light and heat affect human comfort a lot. They may adversely affect for human comfort positively or negatively. Researchers suggest that, human body is used to be comfortable at a temperature of 22oC to 25 oC. Anything lower or higher than this, the human body feels uncomfortable. This is because, the human body is structured in a way that, it should receive a certain amount of light, failure to which it can cause sunburns and other skin conditions.

Refrigeration, the production of cold, is an essential practice for present-day living. It is used in a many place like the processing and preservation of food, conditioning of air for comfort, manufacture of chemicals and other materials, cooling of concrete, medical applications etc. Refrigeration is defined as the science of maintaining the temperature of a particular space lower than its surrounding space. Refrigeration and air conditioning involves various processes such as compression, expansion, cooling, heating, humidification, de-humidification, air purification, air distribution etc. In all these processes, there is an exchange of mass, momentum and energy. All these exchanges are subject to certain fundamental laws. Hence to understand and analyses the refrigeration and air conditioning systems, a basic knowledge of the laws of thermodynamics, fluid mechanics and heat transfer is essential.

Refrigeration is the removal of heat from a space or body at a temperature lower than the surrounding temperature. It should be kept in mind that refrigeration...

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...refrigeration system can be built in capacities well above 1000 tonnes of refrigerant each, which is the largest size for single compressor units.

Comparison between the vapor compression and absorption systems

The comparison between the vapour compression and vapour absorption systems are given in Table 1

S.N. Absorption Cycle Compression Cycle

1 Uses low grade energy like heat. Uses high grade energy like mechanical work.

2 Moving parts are only is the pump, which is a small part of the System. Hence operation is smooth. Moving parts are in the compressor.

Therefore, more wear, tear and noise.

3 The system can work on lower evaporator pressures also without affecting the COP. The COP decreases considerably with

Decrease in evaporator pressure.

4 Automatic operation for controlling the capacity is easy. Automatic operation for controlling the capacity is difficult.