A review on opportunities for the development of heat pump drying systems in South Africa

Abstract

Recently, it has been discovered that heat pump drying is an efficient method of drying for drying industries. Heat pumps deliver more heat during the drying process than the work input to the compressor. Heat pump drying is a more advanced method than the traditional South African industrial and agricultural drying methods, such as direct/indirect sunlight, wood burning, fossil fuel burning, electrical heating and diesel engine heating. Heat pump dryers provide high energy efficiency with controllable temperature, air flow and air humidity and have significant energy-saving potential. In the last decade the market for heat pump systems for water heating and space cooling/heating has grown in South Africa, but the development of heat pumps for industrial and agricultural drying is very slow. As a result of high increases in fossil fuel prices and electricity in South Africa, as well as the problem of CO 2 emissions, green energy, energy saving and energy efficiency are imperative. The development of heat pump drying systems in South Africa is an efficient way to solve energy problems in drying applications as this technology is still in its infancy. We review studies on heat pump drying and compare the methods therein with the most common methods of drying in South Africa.

Energy Study of a Heat Pump Used for Air ( Heating and Dehumidification

“…Analysis of the heat pump verifies that the device is technically viable and provides satisfactory operational conditions for the drying of biological products: air is heated to 48.8°C and dehumidified until a relative humidity of 22.1%. No tests were carried out involving the drying of biological products at this stage, but the operational figures obtained herein agree with several studies on heat pump assisted dryers (Perera, Rahman, 1997;Sosle, 2002;Patel, Kar, 2012;Kivevele, Huan, 2014).…”

Thermal Performance Evaluation of Thermoelectric Module

“…When the vapor pass the cool side, it will condense simultaneously. The result found the distillated water production is 28.5 ml/h with the specific energy consumption of 0.00114 kW h/ml of the 10x10x30 mm 3 evaporation chamber.…”

“…Figure 1. Heat pump VCR dryer (Closed system) [3] From the Fig. 1 show the operation diagram of VCR closed system heat pump dryer that has two path circuits, one is air path and other is refrigerants path, both paths are separated out.…”

Experimental comparative study of an open and completely closed air source heat pump for drying sub-tropical fruits

“…One of the areas of significant escalation in energy consumption is the drying processes required by the agricultural sector particularly that of drying fruits as the demand for South African dried fruits increases [2]. Thus, the introduction of energy efficient and environmental friendly drying technologies is an imperative.…”

“…Thus, the introduction of energy efficient and environmental friendly drying technologies is an imperative. Of late, it has been discovered that HP assisted dyers is an efficient method of drying for drying industries [2,3]. Various research studies have reported that HPD systems are economically feasible with a shorter payback period [4].…”