Thermodynamic Heat Pump Abstract

Thermodynamic Heat Pump

Abstract

Technical knowledge on thermodynamics makes it possible for people toalter the contextual environment to facilitate the performance ofsome tasks. The thermodynamic refrigerator heat pump works byinclining to the second principle of thermodynamic that holds on thepremise that heat energy moves from a cold to hot areas. The idea ofcoldness or hotness is about different contextual environments, andthey may not be standard for all environments. A heat pump uses arefrigerant that has to be non-flammable and easy to turn into liquidand gaseous state. The energy used in the heat pump can be used todetermine its efficiency. For most of the electric heaters, theefficiency is less than one. However, the heat pump has an efficiencygreater than one. The thermodynamic heat pump is applicable in HVACdue to its interchangeable role of providing a cooling and heatingeffect. Its principle is also applicable in plumbing the harness theheat energy in the conditioned environment to reheat the water in apool.

Outline

Introduction- the inevitable nature of human beings to manipulatecontextual environment by changing their temperatures

The heat pump- its main features including the condenser, valve,evaporator, compressor and their functions.

-The importance of a refrigerant in the heat pump

-The efficiency of a heat pump. It is judged by comparing the edgyused as input and the amount of heat energy transferred.

– Increasing the performance of a heat pump by ensuring a minimaltemperature difference to minimize the energy used in the process.

-The application of a heat pump in plumbing and HVAC

Some of the activities that people engage in require a manipulationof the natural environment. Controlling the amount of heat in a workenvironment is a common process in various work environments. Most ofthe offices have air conditioners that help in creating a coolingeffect. People also use refrigerators in their homes to manipulatethe temperatures for a longer storage of food. In implementing suchactivities, the processes exploit the principle of the ability tolower the temperature of a body by using a thermo-electric effect.Due to the poor development of a serious refrigeration method,refrigeration still employs fluid refrigeration that uses therecorded heat engine cycles.

A thermodynamic refrigerator heat pump operates on the principle ofevaporation and condensation that are present in a fluid known as arefrigerant (Nekså 421). The heat pump compresses the fluid to raiseits temperature and releases it through the valve where theabsorption the heat takes place. An increase in temperature of thefluid turns it into a gaseous state after pressurization takes placefor easier circulation throughout the system by the compressor. Thehot and pressurized gas enters the condenser where it cools to amoderately hot gas on the discharge side, where cooling takes place.The cooled fluid moves through the metering device that lowers thepressure and enters the evaporator where it heats and boils. It turnsinto a gas and enters the compressor to continue the cycle (Nekså422).

Theory

To achieve the optimal performance of the heat pump, it is imperativefor the refrigerant to reach a sufficiently high temperature duringcompressing and release it to the condenser. In addition, duringcooling it should reach a sufficiently low temperature. It makes iteasy for sufficient heat to move to the fluid. The pressuredifference must also be sufficient to enhance the condensation of therefrigerant and still evaporate in space with low pressure on thecold side. When the temperature difference is high, the amount ofpressure required to complete the process significantly increases tocompress the refrigerant. It translates to more energy that when thepressure would be low. Therefore, for a heat pump, the coefficient ofperformance lowers with an increase in the temperature difference.For optimum performance, the temperature difference should be asminimal as possible to reduce the amount of energy consumed (Nekså421).

Thermodynamic process in a refrigerator involving the use of a heatpump uses a non-CFC fluid. The fluid evaporates and cools easily, andthis facilitates the cooling effect. A thermodynamic refrigeratorheat pump has several primary parts that include a condenser, anexpansion valve an evaporator and a compressor (Chua and Yang 3613).Heat is transferred to the fluid used in refrigeration, and it turnsit into gas. In the compressor, that uses electrical energy, thetemperature and the pressure of the gas is raised. The pressureforces the gas into the condenser that immediately lowers itstemperature. The temperature in the condenser is much lower than thatof the compressed gas. Therefore, the gas cools, and it turns intothe liquid. The liquid finds its way through the pressure-reducingvalve back to the outdoor evaporator coils (Chua and Yang 3611).

A heat pump can also work in a reversible way whereby it employs areverse valve that reverse the flow of the refrigerant from thecompressor at the condenser and finally to the evaporation coils.During heating, the coil found on the outdoor side is the evaporatorwhile the one on the indoor is the condenser. The refrigerant movesfrom the evaporator and transfers the thermal energy to the externalenvironment. After the refrigerant cools, it absorbs more heat toreheat the outdoor environment, and the cycle continues.

The commonly use refrigerant for the heat pump the refrigerant-22. Ithas several characteristics that make it a preference for use forheat transfer. It can absorb heat and release it fast. Since this isthe most important part of the refrigeration process, refrigerantbecomes the appropriate liquid for use. Also, the liquid isnonflammable and noncombustible and therefore not risk should it besubjected to a flame. However, since it contains chlorine, it isgradually being phased out and replaced by refigerantnt-410A. 410Aharbors the properties of the refrigerant 22 except that it does nothave detrimental effects on the environment (Chua and Yang 3612).

A heat pump moves heat from across sources. The movement of heatusually follows a definite path from a low to high temperaturethrough a mechanical process. A heat pump can, therefore, be simplydefined as a heater when the aim is to warm a place or a refrigeratorif the intention is to provide a cooling effect. According to thesecond principle of thermodynamics, heat cannot spontaneously movefrom a colder environment to a hotter environment (Nekså 421)Therefore, when using a heat pump to transfer energy to achieve thedesired effect, heat moves from when it is more to where it is less.For example, an air conditioner works to provide a cooling effect toa house by moving heat from its cold interior to warm environment inthe room. In addition, a refrigerator transfers heat from thelow-temperature icebox to the warmer room temperature. The processinvolved in the transfer of heat (Qc) from a low to high involveswork input W that is converted to heat transfer. Therefore, thetransfer of heat from a cold to a hot reservoir is summarized asQh=Qc+W (Nekså 423). The heat in the internal environment in arefrigerator gets absorbed into the fluid that evaporates easily. Theprocess lowers the heat in the internal surrounding. To raise thetemperature, the fluid is compressed, and this also increases thepressure. The fluid is cooled to a normal temperature by throughcondensation, and it absorbs the heat. The cycle is repetitive tomaintain a cold environment (Aprhornratana and Eames 245).

It is possible to judge the quality of a heat pump by analyzing theamount of heat transferred (Qh) into the warm place and comparing itwith the work input (W) required. The heat pumps coefficientperformance (COPhp) is defined as COPhp=QhW. That is, itscoefficient of performance is a product of the heat transferred andthe work input involved. The efficiency o a heat engine is alwaysless than one. That is, COPhp=1/Eff (Aprhornratana and Eames 246).Therefore, for a heat engine, efficiency is equal to the work outputdivided by the heat energy transferred. That is, Eff=W/Qh. For a heatpump, COPhp is always greater than one. It means that the heat energytransferred by the heat pump is always more than the work inputrequired for the process to take place. For example, in theeclectically power heat pumps, the amount of transferred heat isusually three or four times more than the electric power consumed tofacilitate the process. The thermodynamic refrigerator heater is moreefficient than a conventional electric heater that produces heatenergy equivalent of the consumed electrical energy.

Applications

The thermodynamic heat pump is used in High Voltage AlternatingCurrent (HVAC). In this application, the heat pump functions a vaporcompression refrigerator that’s has a reversing valve and anoptimized exchanger that allows the reversal of heat flow. It can,therefore, give a heating or cooling effect. The condenser and theevaporator switch functions during the prices and they reflect theefficiency of two separately optimized machines. In plumbing,technicians may use the heat pump to preheat water for swimming poolswhereby the heat energy drawn from the conditioned place may bereused for reheating (Aprhornratana and Eames 248).

Heat pumps are more effective when heating than when cooling in aninterior space when the temperature difference is held equal. Thereason for this is that the energy input to the compressor isconverted into reusable heat when the heat pump is in the heatingmode. For a cooling effect, the condenser is normally outdoors, andthe waste heat is transported to the outdoor using extra inputenergy.

Conclusion

The manipulation of the physical environment is necessary tofacilitate various activities that people engage in every day. Athermodynamic heat pump works to create such an environment byapplying the second law of thermodynamics that state that heat energymoves from a low to high temperature. A heat pump has four mainparts that include the condenser, evaporator, compressor and thevalve. To provide a heating or a cooling effect, the heat pump uses afluid known as a refrigerant that can turn into both liquid andgaseous state with ease. The refrigerant should be non-flammable andeasy to transport since most of the devices that use thethermodynamic heat pump may be portable (Nekså 242). The evaporatorheats up the refrigerant and pushes it to the compressor that givesit pressure. It passes through the valve into the condenser where itcools and liquifies, in the process heat energy is transferred fromthe interior of an environment into the outside environment. Thefunction of the heat pump can also act in reverse to provide aheating effect.

The efficiency of the heat pump is easy to measure by calculating theamount of energy used to transfer the heat. For a heat pump, theefficiency is more than one and this feature makes it different fromother electric heating machines. The optimal efficiency of a heatpump depends on the temperature difference. A big difference intemperature requires more pressure to compress the liquid andtherefore, consumes more energy. The heat pump is applicable as aHigh Voltage Alternating Current due to its capacity for reversalreaction. During cooling and heating the evaporator and the condenserwork interchangeably. Its principle is also applicable in theplumbing to heating water for a swimming pool whereby the heatharnessed from the conditioned environment is used for reheating thewater.

Works Cited

Aprhornratana, S and Eames, Ian. &quotThermodynamic Analysis of Absorption RefrigerationCycles using the Second Law of Thermodynamics Method.&quotInternational Journal of Refrigeration 18.4 (1995): 244-252.

Chua, K. J., S. K.Chou, and Yang, Wenming. &quotAdvances in Heat Pump Systems: AReview.&quot Applied Energy 87.12 (2010): 3611-3624.

Nekså, Petter. &quotCO2 Heat Pump Systems.&quot International Journal of refrigeration25.4 (2002): 421-427.

Annotated Bibliography

Aprhornratana, S., and Eames, Ian. &quotThermodynamic Analysis ofAbsorption Refrigeration Cycles using the Second Law ofThermodynamics Method.&quot International Journal ofRefrigeration 18.4 (1995): 244-252.

The article provides an easy description outlining the second law ofthermodynamics applicable in the absorption cycle in a refrigerator.Eames is an expert of architectural, mechanical and petroleumengineering at the university of Nottingham. The article informs thepaper o the second law of thermodynamics since it is the mainprinciple of action for the heat pump.

Chua, K. J., S. K.Chou, and Yang, Wenming. &quotAdvances in Heat Pump Systems: AReview.&quot Applied Energy 87.12 (2010): 3611-3624.

The article explores the working of a heat pump and the principles ituses. It also details it applications in various daily activities.Chua is a lecturer at the Politecnico Di Milano and Yang is from theUniversity of Singapore with a wealth of experience in mechanical andautomotive engineering. The authors’ work is a reference of how aheat pump works and it applications.

Nekså, Petter. &quotCO2 Heat Pump Systems.&quot International Journal of refrigeration25.4 (2002): 421-427.

The article describes the working of a heat pump by describing themain features and their functions. Neksa is a chief researchscientist at SINTEF Energy Research with a lot of experience inthermodynamic systems. The article informs the paper on the workingof a heat pump and it is a reference when detailing the function ofeach part.