This communication presents finite time thermodynamic optimization of irreversible cascaded refrigeration and heat pump cycles having source/sink thermal reservoirs of finite heat capacitance. A general expression for the optimum coefficient of performance of the refrigerator/heat pump is derived at minimum power input and given cooling/heating load conditions, respectively. External irreversib...

This paper aims at studying a trigeneration system, based on an internal combustion engine and a steam ejector refrigeration system. The designed cycle is to generate cooling and heating energies, and supply power simultaneously. The cycle is studied from thermodynamics point of view and for this purpose, the first law of thermodynamics is applied to all components of the cycle. The efficiency ...

This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO2 and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 C, the energy efficiency of the COOLCEP-S sys...

The temperature of an electronics device rises fairly linearly with increasing device heat flux. This relationship is especially problematic for defense electronics, where heat dissipation is projected to exceed 1000W/cm in the near future. This paper study explored the benefit of cooling the electronics device using indirect refrigeration cooling system .In this system the heat sink in a prima...

The paper focuses on the operation of simple refrigeration cycles. With equipment given, there are, from a control and operational point of iew, five steady-state degrees of freedom; the compressor power, the heat transfer in the condenser, the heat transfer in the evaporator, the choke alve opening and the active charge in the cycle. Different designs for affecting the active charge, including...

The impact of man-made chemicals on the environment, and in particular, the ozone layer, has been investigated over the last 20 years. The phaseout of CFCs under European Regulations and the Montreal Protocol has already taken place and HCFCs are set to follow. A wide range of alternative refrigerants with zero ozone depletion potential have already been developed as replacements for the refrig...

To increase the power efficiency of refrigeration and air conditioning machinery it would be advantageous to be able to run the compressors without any lubricant added to the refrigerant. Without any added lubricant in the refrigerant it would also be possible to simplify the whole refrigeration machinery by excluding all oil handling systems, and there would not any longer be any risk for oil ...

Studied is a kind of NH3/CO2 two-stage low temperature refrigeration system, in which NH3 is used as the refrigerant in the high-temperature stage and CO2 is used as the refrigerant in the low-temperature stage. The performance of the system is simulated and analyzed by changing the mean temperature of the evaporator-condenser and the temperature of the condenser. The mean temperatures of the e...