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Experimental study on the effect of drying air humidity on the performance of a closed-loop heat-pump paddy drying system.

Author(s) : HUANG W., WU W., WANG H., YANG Y., ZHANG H.

Type of article: IJR article

Summary

Heat pump drying (HPD) represents an emerging technology for achieving efficient and quality-preserving drying of paddy, with drying air humidity serving as a critical parameter in the drying process. However, most existing HPD systems lack effective means of regulating dehumidification capacity, thereby making it difficult to precisely control the drying air humidity. Furthermore, research on the effects of drying air humidity on HPD system remains insufficient. To address this issue, this study employed a closed-loop paddy heat pump drying system with a bypass circuit to investigate the impact of drying air humidity on both the system per formance and paddy drying quality. Results indicate that as drying air humidity increased, the average coeffi cient of performance for system (COP sys ) rose continuously while the drying capacity per unit volume per unit time (DCVT) gradually decreased. The average specific energy consumption (SEC) initially decreased and then increased, whereas drying capacity per unit energy consumption (DCEC) showed the opposite trend. Regarding paddy quality, higher drying air humidity continuously reduced the cracked kernel increase rate (Δc) but gradually increased the fatty acid value (FAV). Comprehensive analysis indicated that the optimal supply air humidity was 17.5%. At this condition, average SEC, DCEC, and COP sys of this system were 1.226 (kW⋅h)/kg, 5.10 kg/(kW⋅h), and 8.69, respectively. The Δc and FAV were 7% and 15.01 mgKOH/100 g, respectively. This study elucidates the critical influence of drying air humidity on heat pump system efficiency and paddy drying quality, providing reference for optimizing post-harvest paddy processing technologies.

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Details

  • Original title: Experimental study on the effect of drying air humidity on the performance of a closed-loop heat-pump paddy drying system.
  • Record ID : 30034964
  • Languages: English
  • Subject: Technology
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 188
  • Publication date: 2026/08
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2026.106949

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