Experimental study and modeling of heat pump operating modes in food drying systems

The objective of this study is to experimentally investigate and mathematically model the operation of heat pumps of various scales and capacities in food processing equipment systems. The paper presents the results of an experimental and theoretical study of heat pump operation in food drying systems. Two test setups were developed for the study – one with low (1.465 kW) and one with high (2.4 kW) capacity. Temperature, humidity, and energy parameters were studied, and an industrial experiment was conducted on an industrial fish drying unit. The units utilized a closed-loop air recirculation system with heat recovery, microchannel heat exchangers, and automated microprocessor control. Experiments have shown that the use of heat pumps reduces energy consumption by 50–70 % compared to traditional electrical methods by reusing the heat of moisture condensation and optimizing compressor operating modes. Mathematical models developed based on heat and mass transfer equations relate the dependencies of condensation temperatures, the degree of air dehumidification, and the power consumption. A 10 °C reduction in con-densation temperature reduces energy costs by 15 %, but requires increased airflow to compensate for the reduced drying effect. In an industrial installation, implementing recirculation and periodic supply of cool outside air reduced energy consumption by 25 %. Particular attention is paid to the initial drying stage, where the heat pump load is highest due to intense moisture release. Analysis of the process kinetics con-firmed the exponential nature of moisture content reduction, as described by a first-order model. The practical significance of the study is supported by industrial test data. The results demonstrate the po-tential of heat pumps for creating environmentally friendly and cost-effective drying systems. The proposed solutions can be scaled up for food industry enterprises.