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This paper experimentally studied the effects of different factors of electrohydrodynamics-heat pump combined drying on the drying characteristics of banana slices. Results showed that: The introduction of high-voltage electric field in heat pump drying could increase the drying rate of banana slices, and it would increased with the increasing of voltage. Banana slices showed better drying quality under combined drying. Compared with 60 ℃ single heat pump, the energy consumption of 60 ℃, 75 kV electrohydrodynamics-heat pump drying was reduced by 7.61 kJ/g. In addition, by fitting different drying models, the fitting effect of the Page model was the best, which could better describe the moisture change rule of banana slices during electrohydrodynamics-heat pump combined drying. It was suggested that, the electrohydrodynamics could help speed up the drying rate while improving the drying quality, reducing drying energy consumption, and save energy, which could provide reference value for the application of electrohydrodynamics drying technology.

The drying characteristics of yam slices using heat pump-electrohydrodynamics (EHD) combined drying were studied under the conditions of the drying temperatures of 50–60 °C, the voltages of 80–100 kV and the wind speeds of 1∼3 m/s. The results show that compared with the single heat pump drying, the combined drying can effectively reduce the drying temperature by approximately 5 °C. This is relatively friendly to heat sensitive materials and can also improve the running performance of the heat pump system. Furthermore, the sensory score is increased by approximately 21.4% and the specific energy consumption of combined drying at the voltage of 100 kV is reduced by approximately 27.8%. Under the later stage of the combined drying, the wind speed can be reduced to save energy consumption. Through the analysis of model parameters, Page model is more consistent with the variation law of drying experimental data. This paper provides practical guidance for optimizing the process of yam slices using heat pump-EHD combined drying.

In this paper, the feasibility of two low global warming potential refrigerants R513A and R1234yf as alternatives to R134a was tested in an automotive air conditioning system in winter. The test results showed that the heating capacities of R513A and R1234yf were 2% and 4% lower than that of R134a, and their COP were 3-9% and 6-19% lower than that of R134a, respectively. It revealed that R513A can be used as a transition product to replace R134a, and R1234yf required further improvements to improve the energy efficiency. [ABSTRACT FROM AUTHOR]