Adsorption Refrigeration

What is adsorption refrigeration?

Key facts

Adsorption is a heat driven cooling process. It uses an adsorption medium such as activated carbon together with a refrigerant to achieve a cooling effect. It uses a chemical rather than a mechanical compressor and is driven by heat rather than mechanical work. The operation of adsorption heat pumps and refrigerators is based on the ability of porous solids (the adsorbent) to adsorb vapour (the adsorbate or refrigerant) when at low temperature and to desorb it when heated. Although the heating and cooling provided by a single generator is discontinuous, it can be made continuous by operating two or more generators out of phase.

Applications

Refrigeration, air conditioning and heat
pumps eg:

  • Solar or biomass powered
  • refrigeration & air conditioning
    Vehicle (mobile) air conditioning from
    waste engine heat

  • Domestic gas fired heat pumps

Benefits

Has the potential to reduce the
environmental impact of cooling:

  • Heat powered cycles can make use
    of renewables or waste heat as well
    as conventional fuels to reduce CO2
    emissions

  • Refrigerants used are natural working
    fluids with low GWP/ODP

Challenges

Research work is focused on improving performance in
these two main areas:
The basic adsorption cycle has low efficiency,

  • however, recovery of heat between adsorbent
    beds can give good performance

  • Low thermal conductivity of available adsorbent
    materials can lead to large sized equipment but
    innovative heat exchanger design can overcome
    the problem

How far is it from the market?

Sorption Energy is a spin-out company intended to bring
the latest machines to market. This is timely competition
for the likes of Vaillant and Viessmann who plan to launch
gas fired heat pumps in spring/summer 2010.

Who is leading this research in the UK?

University of Warwick, Sustainable Energy Engineering
and Design research group led by Bob Critoph

To view the  full case study click here.