Heat Pumps in agriculture and horticulture
A heat pump is a heating mechanism that that can acquire low temperature heat and upgrade it to a higher, more useful, temperature by using a simple refrigeration process. The low temperature heat can come from many sources including the soil, water or the outside air.
An investigation is underway to determine the benefits of using an air source heat pump (ASHP) to pre-heat the hot water used in a dairy unit. An ASHP has a slightly lower efficiency than a ground source heat pump but it is easier and cheaper to install.
The coefficient of performance (COP) is a key measure of the benefits obtained by using a heat pump. The COP is the ratio of the energy produced by the pump to the energy used to work the pump. The COP will vary depending on the temperature difference between the air supplying the heat and the water which is absorbing the heat.
Tests carried out by the Dundalk Institute of Technology on an installation on the east coast of Ireland showed a COP of 2.75 in February 2009 as compared with 4.5 in June 2009. A domestic case study carried out by Action Renewables in Feb/March 2007 showed the COP varying from 3.73 (external temp 8.50C) to 2.8 (external temp 2.10C).
Further details of heat pumps and the progress of the investigation at CAFRE are available from Garrett O'Sullivan at garrett.osullivan@dardni.gov.uk and 028 9442 6869.
