Drying is an essential process in the agro-food industry to produce shelf-stable products. However, it is an energy consuming process that uses fossil fuels for its energy generation. These issues have motivated research in novel drying techniques that can be more efficient and less harmful to the environment. One of such technologies is the heat pump dehydrator.
A heat pump dehydrator works by utilizing a compressor to vaporize water in the evaporator to raise its temperature and pressure. It then passes to the heat exchanger to transfer the heated air to the ambient air. Moreover, the refrigerant in the heat pump dehydrator absorbs the humidity from the air and converts it into liquid to be pumped back to the evaporator to be vaporized again. As a result, the cycle repeats continuously until the desired moisture level is reached.
Compared to conventional hot air drying methods, the heat pump dehydrator has higher energy efficiency and lower operating cost. Moreover, it has low temperature drying and provides high quality dried products. In addition, it can save up to 30% of fossil energy and electricity costs compared to traditional drying processes.
Despite its benefits, little study has been conducted on the evaluation of the performance of heat pump dehydrator. Early studies mainly focused on the performance of the heat pump itself, such as its heating and cooling efficiency or thermal efficiency. It is suggested that a more holistic approach is needed to evaluate the performance of heat pump assisted drying. For instance, exergy analysis can be used to determine the amount of energy required for dehumidification and the unavoidable losses in the heat pump dehydrator.