An in-rack cooling system connected to an external vapor recompression loop can be an economical solution to harness waste heat recovery in data centers. Validated subsystem-level models of the thermosyphon cooling and recompression loops (evaporator, heat exchangers, compressor, etc.) are needed to predict overall system performance and to perform design optimization based on the operating conditions. This paper specifically focuses on the model of the evaporator, which is a finned-tube heat exchanger incorporated in a thermosyphon cooling loop. The fin-pack is divided into individual segments to analyze the refrigerant and air side heat transfer characteristics. Refrigerant flow in the tubes is modeled as 1-D flow scheme with transport equations solved on a staggered grid. The air side is modeled using differential equations to represent the air temperature and humidity ratio and to predict if moisture removal will occur, in which case the airside heat transfer coefficient is suitably reduced. The louver fins are modeled as individual hexagons and are treated in conjunction with the tube walls. A segment-by-segment approach is utilized for each tube and the heat exchanger geometry is subsequently evaluated from one end to the other, with air property changes considered for each subsequent row of tubes.more »
RACK-LEVEL THERMOSYPHON COOLING AND VAPOR-COMPRESSION DRIVEN HEAT RECOVERY: EVAPORATOR MODEL
An in-rack cooling system connected to an external vapor recompression loop can be an economical solution to harness waste heat recovery in data centers. Validated subsystem-level models of the thermosyphon cooling and recompression loops (evaporator, heat exchangers, compressor, etc.) are needed to predict overall system performance and to perform design optimization based on the operating conditions. This paper specifically focuses on the model of the evaporator, which is a finned-tube heat exchanger incorporated in a thermosyphon cooling loop. The fin-pack is divided into individual segments to analyze the refrigerant and air side heat transfer characteristics. Refrigerant flow in the tubes is modeled as 1-D flow scheme with transport equations solved on a staggered grid. The air side is modeled using differential equations to represent the air temperature and humidity ratio and to predict if moisture removal will occur, in which case the airside heat transfer coefficient is suitably reduced. The louver fins are modeled as individual hexagons and are treated in conjunction with the tube walls. A segment-by-segment approach is utilized for each tube and the heat exchanger geometry is subsequently evaluated from one end to the other, with air property changes considered for each subsequent row of tubes. Model more »
- Award ID(s):
- 1738782
- Publication Date:
- NSF-PAR ID:
- 10287016
- Journal Name:
- Proceedings of the ASME 2021 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems InterPACK2021
- Sponsoring Org:
- National Science Foundation
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