Off-Design Modeling and Operational Optimization of Trans-Critical Carbon Dioxide Heat Pumps

Performance Investigation of Two Two-Stage Trans-Critical Carbon Dioxide Refrigeration Cycles Ejector and Internal Heat Exchanger

In the present work, the performances of improved two-stage multi inter-cooler trans- critical carbon dioxide (CO2) refrigeration cycles with ejector and internal heat exchanger have been examined. In the new improved cycles, an internal heat exchanger is append to the cycles. Also, second inter-cooler in improved cycles, cooled with the refrigeration of the cycle, so that in first c...

Economic optimization and comparative study of solar heat pumps

In this paper, an economic study of solar heat pumps and an investigation of differences between solar heat pumps and conventional heat pumps—based on their performances and energy consumption—are conducted for a residential apartment located in Austin, Texas, USA. Heating in the apartment is provided via a solar heat pump during the cold months of a year. Solar collectors are used to meet the ...

Some Modeling Improvements for Unitary Air Conditioners and Heat Pumps at Off-Design Conditions

Models for unitary air conditioners and heat pumps typically have difficulties in providing accurate predictions for the following situations: 1) charge modeling over a large range of charge levels, 2) two-phase refrigerant entering fixed-orifice expansion devices, 3) two-phase refrigerant entering compressors, and 4) non-uniform refrigerant mass flow allocation among evaporator circuits at low...

Heat Stroke and Carbon Dioxide

Thermoacoustic Heat Engine Modeling and Design Optimization∗

Thermoacoustic heat engines (TAEs) are potentially advantageous drivers for thermoacoustic refrigerators (TARs). Connecting TAEs to TARs means that waste heat can effectively be utilized to provide cooling, and increase overall efficiency. However, this is currently a niche technology. Improvements can be made through a better understanding of the interactions of relevant design parameters. Thi...