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Development of a refrigerant to refrigerant heat exchanger for high efficiency CO2 refrigerant cycle.

Number: pap. 2202

Author(s) : KAJI R., YOSHIOKA S., FUJINO H.

Summary

The cycle performance of CO2 refrigerant is worse than that of HFCs since the working pressure is higher which suffers larger compression and expansion losses. To enhance the cycle performance similar extent to HFCs, refrigerant to refrigerant heat exchangers need to be applied as one of the many components equipped into the CO2 cycle. However, when such a heat exchanger is used as an economizer, which works between high temperature refrigerant after the gas cooler and low temperature refrigerant by reducing to the intermediate pressure, it is confirmed from the visualization that the refrigerant in low temperature side is observed as a vapor-liquid dispersed flow. In such a condition, the evaporating performance is low since most liquid flows in the vapor core as droplets. In this study, aiming at weight saving and compactness for a refrigerant to refrigerant heat exchanger as an economizer, a newly designed aluminum double-tube heat exchanger in which outer channel is formed by multiports instead of annulus is introduced. Spiral fins are applied in the surface of inner channel to aim for attaching liquid flowing in vapor core to the inner tube wall. The local heat transfer coefficient was experimentally measured in a single tube and the performance of a heat exchanger assembly was estimated. These results show that this newly designed heat exchanger is effective to enhance heat transfer performance.

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Pages: 8

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Details

  • Original title: Development of a refrigerant to refrigerant heat exchanger for high efficiency CO2 refrigerant cycle.
  • Record ID : 30018928
  • Languages: English
  • Source: 2016 Purdue Conferences. 16th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2016/07/11

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