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Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. [1] A heat pump is a mechanical system that transmits heat from one location (the "source") at a certain temperature to another location (the "sink" or "heat sink") at a higher temperature. [2]
Familiar examples are the upward flow of air due to a fire or hot object and the circulation of water in a pot that is heated from below. Forced convection : when a fluid is forced to flow over the surface by an internal source such as fans, by stirring, and pumps, creating an artificially induced convection current.
The choice of working fluids is known to have a significant impact on the thermodynamic as well as economic performance of the cycle. A suitable fluid must exhibit favorable physical, chemical, environmental, safety and economic properties such as low specific volume (high density), viscosity, toxicity, flammability, ozone depletion potential (ODP), global warming potential (GWP) and cost, as ...
The refrigeration cycle uses four essential elements to cool, which are compressor, condenser, metering device, and evaporator. At the inlet of a compressor, the refrigerant inside the system is in a low pressure, low temperature, gaseous state.
In refrigeration systems, subcooling the refrigerant is necessary to ensure the completion of the remaining stages of the refrigeration cycle. The subcooling stage provides certainty that the refrigerant is fully liquid before it reaches the next step on the cycle, the thermal expansion valve , where the presence of gas can be disruptive. [ 1 ]
Fig. 6 The four stages in the cooling cycle of the GM cooler. The cycle can be divided in four steps, with Fig.6, as follows: The cycle starts with the low-pressure (LP) valve closed, the high-pressure (HP) valve open, and the displacer all the way to the right (so in the cold region). All the gas is at room temperature. From a to b.
Examples include the Liebig condenser, Graham condenser, and Allihn condenser. This is not to be confused with a condensation reaction which links two fragments into a single molecule by an addition reaction and an elimination reaction. In laboratory distillation, reflux, and rotary evaporators, several types of condensers are commonly used ...
A device that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This cooled liquid flows through pipes in a building and passes through coils in air handlers, fan-coil units, or other systems, cooling and usually dehumidifying the air in the building. Chillers are of two types; air-cooled or water-cooled.