Study on dehumidification performance of closed-loop heat pump drying system with evaporator bypass

MA Longteng; XIA Peng; SUN Heng

doi:10.12299/jsues.24-0341

Volume 40 Issue 2

Jun. 2026

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Article Navigation > Journal of Shanghai University of Engineering Science > 2026 > 40(2): 215-221

MA Longteng, XIA Peng, SUN Heng. Study on dehumidification performance of closed-loop heat pump drying system with evaporator bypass[J]. Journal of Shanghai University of Engineering Science, 2026, 40(2): 215-221. doi: 10.12299/jsues.24-0341

Citation:

MA Longteng, XIA Peng, SUN Heng. Study on dehumidification performance of closed-loop heat pump drying system with evaporator bypass[J]. Journal of Shanghai University of Engineering Science, 2026, 40(2): 215-221. doi: 10.12299/jsues.24-0341

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Study on dehumidification performance of closed-loop heat pump drying system with evaporator bypass

doi: 10.12299/jsues.24-0341

School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China

Received Date: 2024-11-21
Available Online: 2026-08-19
Publish Date: 2026-06-30

Abstract

Abstract

Closed-loop heat pump drying system face the issues of insufficient dehumidification capacity when processing high moisture materials. To enhance the dehumidification capacity and improve the drying efficiency, a closed-loop heat pump drying system with an evaporator bypass was proposed. Mathematical models of the heat pump system and drying process were established. The drying system was simulated using engineering equation solver (EES) to analyzed dehumidification performance and select suitable refrigerants. The results demonstrate that at a bypass ratio of 0.8, the specific moisture extraction rate (SMER) increases by 20.1% to 28.7% (averaging 23.9%), while the coefficient of performance (COP) decreases by only 7.53% to 7.66%. Incorporating a bypass significantly improves the system's dehumidification performance and drying efficiency. Using COP and SMER as indicators, the performance of four refrigerants under different working conditions was compared, identifying R1234ze(E) as the optimal refrigerant. The system model was validated experimentally, with relative errors between simulated and measured values remaining within 10%. These findings provide a reference for the optimal design of closed-loop heat pump drying systems.
- heat pump drying,
- air bypass,
- dehumidification rate,
- performance optimization.

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References(20)

References

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