Whenever food products are dried or cured there are usually large amounts of energy involved, often a considerable part of the cost of production.
The exhaust of warm moist airstreams can present opportunities for the recovery of significant amounts of that energy using heat exchangers.
One of the cost effective heat exchangers available are the air conditioning style coils developed more than 50 years ago as a light weight and inexpensive method of moving thermal energy to and from an air stream using a fluid contained in simple copper pipes.
The air conditioning style coils utilise aluminium fins on the airside to provide an extended surface. They can be custom made to fit the application and the configurations available are flexible with regard to size, fluid flow arrangement and fin spacing.
It is possible to assemble a versatile air-to-air heat exchange system using these devices, called a ‘run-around’ or thermal loop energy recovery system.
The thermal loop energy recovery system from Hendy Coils have been successfully applied in Australia to dehumidification, drying and curing applications in many industries including food processing, timber drying, packaging and others.
The thermal loop energy recovery basic systems consist of two regular style air conditioning water coils placed in separate air streams of differing temperatures. A small pump circulates a coupling fluid in a loop between the coils and an expansion tank allows for temperature changes. The coupling fluid in most cases can be water and corrosion inhibitors are not required if copper pipe and a compatible pump are selected.
Run-around systems have a number of advantages over other types of air-to-air energy recovery equipment. The airstreams do not have to be adjacent or in any particular orientation and there is no possibility of cross contamination of airflows. Reasonably long distances without loss of performance can separate them provided interconnecting pipe work is well insulated. Under certain circumstances latent heat can be recovered, but moisture transfer between the airstreams cannot happen. The systems are controllable so heat transfer can be regulated or stopped if desired.