Transcritical Carbon Dioxide Refrigeration as an Alternative to Subcritical Plants

2016 ◽  
pp. 100-159
Author(s):  
Adriana Greco ◽  
Ciro Aprea ◽  
Angelo Maiorino
Keyword(s):  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Critical Temperature ◽  
Experimental Analysis ◽  
Internal Heat ◽  
Refrigeration Cycle ◽  
Desiccant Wheel ◽  
Internal Heat Exchanger ◽  
Transcritical Carbon Dioxide ◽  
Vapour Compression

Carbon dioxide (R744) is as a valid alternative to classical substances such as HFCs used in vapour compression plants. A transcritical refrigeration cycle is needed because the critical temperature of carbon dioxide is usually lower than the ambient temperature. In this chapter the performances of a transcritical cycle have been evaluated with a prototype R744 system working as a classical spit-systems to cool air. An experimental analysis has been carried out on the effect of: refrigerant charge, internal heat exchanger, heat rejection pressure on the energetic performances of the transcritical plant. An experimental analysis of a hybrid trans-critical refrigerator-desiccant wheel system has been carried out in order to improve the COP. The experimental transcritical cycle has been examined in comparison with a classical vapour compression plant working with the R134a.

Transcritical Carbon Dioxide Refrigeration as an Alternative to Subcritical Plants

2015 ◽  
pp. 295-359
Author(s):  
Adriana Greco ◽  
Ciro Aprea ◽  
Angelo Maiorino
Keyword(s):  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Critical Temperature ◽  
Experimental Analysis ◽  
Internal Heat ◽  
Refrigeration Cycle ◽  
Desiccant Wheel ◽  
Internal Heat Exchanger ◽  
Transcritical Carbon Dioxide ◽  
Vapour Compression

Carbon dioxide (R744) is as a valid alternative to classical substances such as HFCs used in vapour compression plants. A transcritical refrigeration cycle is needed because the critical temperature of carbon dioxide is usually lower than the ambient temperature. In this chapter the performances of a transcritical cycle have been evaluated with a prototype R744 system working as a classical spit-systems to cool air. An experimental analysis has been carried out on the effect of: refrigerant charge, internal heat exchanger, heat rejection pressure on the energetic performances of the transcritical plant. An experimental analysis of a hybrid trans-critical refrigerator-desiccant wheel system has been carried out in order to improve the COP. The experimental transcritical cycle has been examined in comparison with a classical vapour compression plant working with the R134a.

scholarly journals Experimental evaluation of an internal heat exchanger in a CO2 subcritical refrigeration cycle with gas-cooler

2015 ◽  
Vol 80 ◽  
pp. 31-41 ◽  
Author(s):  
Rodrigo Llopis ◽  
Carlos Sanz-Kock ◽  
Ramón Cabello ◽  
Daniel Sánchez ◽  
Enrique Torrella
Keyword(s):  
Heat Exchanger ◽  
Experimental Evaluation ◽  
Internal Heat ◽  
Refrigeration Cycle ◽  
Internal Heat Exchanger

Performance characteristics of natural-refrigerants- based ejector expansion refrigeration cycles

2009 ◽  
Vol 223 (5) ◽  
pp. 543-550 ◽  
Author(s):  
J Sarkar
Keyword(s):  
Heat Exchanger ◽  
Internal Heat ◽  
Area Ratio ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Internal Heat Exchanger ◽  
Optimum Parameters ◽  
And Performance ◽  
Vapour Compression ◽  
Cycle Temperature

The thermodynamic analyses and comparison of three natural-refrigerants-based vapour compression refrigeration cycles (ammonia, isobutane, and propane) are presented in this article using a constant pressure mixing ejector as an expansion device. Optimization of the area ratio of the ejector is done based on maximum cooling coefficient of performance (COP) and performance improvement for different operating conditions. The effect of using an internal heat exchanger is studied as well. Results show that optimum area ratio and cooling COP increases with a decrease in cycle temperature lift, whereas the COP improvement over basic expansion cycle increases with the increase in cycle temperature lift. Study shows that the optimum parameters, as well as performance using the ejector as an expansion device, are strongly dependent on the refrigerant properties as well as the operating conditions. The optimum area ratio is maximum for ammonia and minimum for propane, whereas maximum cooling COPs are similar. Using the ejector as an expansion device, propane yields a maximum COP improvement of 26.1 per cent followed by isobutane (22.8 per cent) and ammonia (11.7 per cent) for studies ranges. The effect of using an internal heat exchanger in the ejector expansion refrigeration cycle is found to be not profitable.

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