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| Defrost of Heat Exchangers Using Secondary Refrigerant |
| Received:May 07, 2018 Revised:July 25, 2018 |
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| DOI：10.7643/ issn.1672-9242.2018.07.011 |
| KeyWord:climatic environmental test chamber secondary refrigerant frost-heat exchanger multiple fin pitch defrost |
| Author | Institution |
| MA Jian-jun |
Aircraft Strength Research Institute of China, Xi'an , China |
| LIU Hai-yan |
Aircraft Strength Research Institute of China, Xi'an , China |
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| Abstract: |
| Objective To solve the frost problem of heat exchangers used in extreme low temperature climatic test chamber with liquid secondary refrigerant as coolant to obtain feasible design scheme for defrost. Methods Based on the aspects of restrain-frost and defrost, two defrost systems including variable fin spacing frost-heat exchanger were designed and studied by experiment. Results The windward side of the variable fin spacing frost-heat exchanger frosted heavily while the leeward frosted lightly. Defrost time consumed by inner-defrost system was 3.5min while out-defrost system needs 7min. In combination with replacement of refresh air, water retained on the surface of frost-heat exchanger could be removed in 20min by flowing heat after inner-frost. Conclusion The variable fin spacing frost-heat exchanger can pre-dehumidify the air and protect the main heat exchanger. The inner-defrost system with good inner defrosting effect supported by fresh air purging and with steam as the heat source is successfully applied in large climatic environmental test laboratory. |
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