HEAT PUMPs

Heat pumps make use of the refrigeration cycle. They rely on the specific property of a refrigerant to evaporate at a desired temperature, using ambient energy. The majority of heat pumps sold today use fluorinated hydrocarbons (F-gases, HFCs) to run. The specific properties of these chemicals make them suitable for an efficient process contributing to energy savings4.

heat-pumps

More importantly, the possible leakage of heat pumps is overcompensated by their benefits of reducing emissions due to their energy use, meaning that heat pumps using HFCs are appropriate applications to contribute to a reduction in overall GHG emissions when compared to conventional heating technologies.

In 2013 there were 6.7 million heat pump systems working in Europe according to the latest report from European Heat Pump Association (EHPA) which represents 21 countries. Yearly sales have increased from 446,000 units in 2005 to 771,000 units in 20135.. Air-to-air units made up around half this total.

Heat pumps are used in a wide range of applications in the EU for residential, commercial and industrial use for heating and hot water production. Heat pumps use renewable energy by extracting heat from the air water or ground depending on the type of heat pump installed. They deliver about three times the amount of energy compared to what they consume in electricity. Heat pump tumble driers are electric powered and are typically 40% more efficient than the most efficient condenser electric tumble dryers. Typically non-flammable HFCs are used as the refrigerant for the heat pump in a hermetic system6.

The industrial heat pumps sector is growing quickly because it addresses several sustainability issues simultaneously: energy savings, reduction of GHG emissions and increased use of renewable energy.

Industrial heat pump systems have heat delivery rates from 100 kW to over 100 MW, with the heat source usually at ambient temperature or the waste heat temperature of an industrial process. Very large systems are used for district heating systems, with many examples in Scandinavia. The smallest of these systems are about 5 000 kW. Most installations use HFC-134a in centrifugal compressors, with some (up to 15 000 kW) using R-717. The largest is in Stockholm, with a total capacity of 180 000 kW (180 MW) using HFC-134a in centrifugal compressors.

 

This system takes heat from sea water to provide the thermal source; other similar installations have used waste water from the sewage system. [UNEP 2014 Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options Committee].

Currently the majority of heat pumps use HFC-410A.

F-Gas Regulation and Heat Pumps

Regulation 517/2014 on Fluorinated Greenhouse Gases contains measures that apply to heat pumps containing HFCs. These are all the measures that have the objective of reducing emissions through leakage checking, recovery, and training and certification. While the HFCs used in heat pumps and, from 2017, for imported pre-charged heat pumps must be within the HFC quota system, there are no placing on the market restrictions for heat pumps. This recognises the valuable role of HFCs as refrigerant for heat pumps7.

Impacts of Leakage from Refrigerants in Heat Pumps

A recent report for the UK Department of Energy and Climate Change addresses the net benefit of heat pumps in the UK, taking into account the environmental costs associated with refrigerant leakage. The primary research and modelling indicated that whilst leakage led to significant CO2 emissions, this was nonetheless a small proportion of the total reduced emissions associated with heat pump technologies. It also highlights that there is scope to reduce leakage further, thereby increasing the net benefit associated with heat pumps.

Some of the key findings from the study are as follows:

It was determined from analysis of F-gas log books that annual leakage rates from operation of heat pumps were of the order of 3.8% of installation charge for non-domestic applications and 3.5% for domestic applications. However these log books were generally of poor quality, leading to significant uncertainty within the modelling of this data.

 

Optimum charging has an impact on energy efficiency performance. Tests suggest that a refrigerant charge reduction of 10% would lead to a relative coefficient of performance (COP) reduction of about 3% in heating and 15% in cooling operation respectively. Undercharging the heat pump by 40% would reduce the relative COP by around 45% in heating mode and 24% in cooling operation. For the heating mode in particular this is a very significant reduction in performance.

 

The roll-out of heat pumps provides benefits in terms of their replacement of existing fossil fuel heating technologies. This benefit is determined by calculating the reduction in CO2 emissions compared to these counterfactual technologies. The results of this analysis show that for the UK the level of benefit is an order of magnitude greater than the emissions associated with refrigerant loss.

hfcs

4European Heat Pump Association Heat Pump Booklet Second Edition 2014
5 European Heat Pump Association Market and Statistics Report 2014
6PUT THIS IN A BOX? The Heat Pump Tumble Dryer is an electric powered tumble dryer which is typically 40% more efficient than the most efficient condenser electric tumble dryers. In a standard electric tumble dryer, there is a heating element and a motor. A condensing dryer uses a , the hot moist air from the drum is blown through a passive heat exchanger which cools the hot moist air so that water condenses and is collected in a removable container. The still warm, but now dry air is then re-circulated past the heating element into the drum. A heat pump tumble dryer heats the air with a heat pump instead of a conventional heating element, removes the heat from the hot moist air and recycles the heat.Typically non-flammable HFCs are used as the refrigerant for the heat pump in a hermetic system.
7 Impacts of Leakage from Refrigerants in Heat Pumps, Eunomia Research & Consulting Ltd and the Centre for Air Conditioning and Refrigeration Research (London Southbank University) March 2014