What is an industrial heat pump?
A refrigeration system basically takes the heat from a product or room and discharges this energy at a higher temperature through a condenser and in doing so energy is added in driving pumps, fans and compressors. This additional energy is also discarded at the condenser. If there is an evaporative condenser a certain amount of chemically treated water is also consumed, with approximately 1/3rd of the volume of water being discharged as effluent.
When a heat pump is added, the refrigerant gas is compressed further, from the condensing temperature, up to a useful temperature where the condensing effect is produced with water (recovered) rather than discharging it to the ambient at the condenser (lost). In fact even the energy used to drive the heat pump is recovered.
In an ideal world, if the heat pump load (heating requirement) matched the cooling load, then there would be no need to use the evaporative condenser, or the boiler and the energy would purely move round the system and change temperature from time to time (thus the term “Heat pump”)
Heat pump on main refrigeration plant
A high temperature hot water heat pump is a mechanism for the recovery of waste heat from existing centralised site refrigeration systems to generate hot water which can subsequently be used to heat processes like pasteurisers and CIP. It takes low grade heat from the hot pressurised refrigerant gas which would normally be discharged to atmosphere at around 30°C, and using a secondary high pressure compressor system, upgrades it to a condensing temperature which can heat up water via a heat exchanger to a maximum 90°C.
Using a buffer tank and pumps, the hot water is distributed around the factory, (in a similar fashion to that of a regular chilled water system – but hot) and is used as a heat source for processes.
The food and drink sector
In the food and drink sector in the UK there are currently a handful of examples of hot water heat pumps but these are limited to food manufacturers that have a requirement for large volumes of 50°C – 60°C wash down water.
The first example of a heat pump using refrigeration condenser heat as a low temperature source is in a dairy in the North West of England; however the technology is commonly used in various businesses on the Continent.
Currently steam raised by firing a boiler is normally used as a heating medium in dairies and has an efficiency of 60% – 80% for useful output. A heat pump producing 80°C water has a COP of just over 5; or in other words, an efficiency of around 500% heat output to electrical energy in.
When the relative costs of fuel and electricity are taken into account, as well as the different carbon intensities of the different energy sources, a significant saving in carbon emissions and costs is made over existing technology.
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If you think this type of technology might be applicable to your company, please get in touch. We have wide ranging refrigeration experience and are able to advise impartially on many different technologies.