Refrigeration cycle pdf

The above figure shows the objectives of refrigerators and heat pumps. The purpose of a refrigerator is the removal of heat, called the cooling loa from a low-temperature medium. Mechanical refrigeration works by changing the The majority of heat is removed from the The majority of the works by removedchanging the absorbed heat is state of the refrigerant.

In the past, this was done by collecting ice in the winter and using its specific heat to cool as the ice melted. When pound of ice melts, it absorbs 1Btu, as latent energy. So refrigeration cycle should be known to understand the refrigeration system. Some basic refrigeration cycles are discussed here through different diagrams. VAPOUR COMPRESSION CYCLE Vapour compression cycle is an improved type of air refrigeration cycle in which a suitable working substance, termed as refrigerant , is used.

Refrigeration cycle is the basis of all refrigeration systems. REFRIGERATION CYCLES Carnot Cycle We start discussing the well-known Carnot cycle in its refrigeration mode. Figure 1: Carnot Cycle In this cycle we define the coefficient of performance as follows: LL HL qT COP wT T == − (1) Which comes from the fact that wq q= HL− (first law) and qTsLL= Δ , qTsHH=Δ (second law). The vapor-compression refrigeration is the most widely used cycle for refrigerators , air- conditioners, and heat pumps.

Schematic for ideal vapor-compression refrigeration cycle. Heat reclaim, heat recovery or energy conservation occurs when the heat is sent to an area where it is needed or desired. Since refrigeration deals completely with the transfer of heat, to better understand how the refrigeration process works, it is necessary to first understand the nature of HEAT. Refrigerant can change state from vapor (by absorbing heat) to liquid (by condensing that heat).

Basic refrigeration cycle principles: 1. As refrigerant in the latent state or as vapor refrigerant in the process of changed state to liqui this is the phase where it absorbs or rejects large quantities of heat. Carnot cycle requires a compressor that can handle two-phases 2- also process 4-involves expansion of two-phase flow in a turbine. Air or gas expansion systems. In an air or gas expansion system, air or gas is compressed to a high pressure by mechanical energy. It is then cooled and expanded to a low pressure.

Because the temperature of air or gas drops during expansion, a refrigeration effect is produced. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members are available on request.

Find out how the refrigeration cycle works. Liquids absorb heat when changed from liquid to gas. Gases give off heat when changed from gas to liquid.

For an air conditioning system to operate with economy, the refrigerant must be used repeatedly. The cooler refrigerant in the evaporator tubes, absorb the warm room air. The change of temperature causes the refrigerant to “flash” or “boil”, and changes from a low pressure liquid to a low pressure cold vapor.

The low pressure vapor is pulled into the compressor and the cycle starts over. The transcritical cycle process begins with a one- stage compression from state point to 2. During this process, the temperature rises significantly – an for carbon dioxide, can reach a level of 130°C.