IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask C1 Report, 31 October 2010
A new development of a system concept called ECOS (Evaporatively cooled sorptive heat
exchanger) for small air-flow capacities up to 400 m³/h is currently developed at Fraunhofer
ISE. The ECOS system concept consists of two air-to-air plate heat exchangers which unite
air dehumidification by adsorption and air cooling by indirect evaporative cooling in a single
component. An operational scheme is given in Figure 32.
The plate heat exchanger is divided into desiccant-coated sorptive channels and cooling
channels which are in thermal contact. Ambient air passing the sorptive channels is
dehumidified and simultaneously cooled by indirect evaporative cooling. This is achieved
through evaporation of water sprayed into the cooling channels. Therefore, the heat of
adsorption is removed. This leads to the cooling of the sorptive matrix and to an enhanced
sorption capacity in comparison to adiabatic processes such as in a dehumidifier wheel. In
order to provide a continuous supply air flow to the building, the two heat exchangers are
operated alternately – while one heat exchanger is in adsorption mode providing air
dehumidification and cooling, the second heat exchanger is regenerated and pre-cooled. The
main advantages of the ECOS cooled sorptive heat-exchanger concept are the enhanced
dehumidification, the simultaneous air cooling and dehumidification and the strict separation
of the supply and the return air flow, avoiding carry-over effects common in rotary DEC
systems.
Ambient
air
active
1
2 3
Return
air
Exhaust
air
4 5
7 8
Supply
air
6
9 10
Figure 32: ECOS system concept: regeneration of the upper heat exchanger and ambient air
dehumification and cooling in the lower heat exchanger.
Corresponding researchers:
Hans-Martin Henning: Hans-Martin.Henning@ise.fraunhofer.de
Alexander Morgenstern: Alexander.Morgenstern@ise.fraunhofer.de
Constanze Bongs: Constanze.Bongs@ise.fraunhofer.de
Relevant publications:
[161] Motta, M., Henning, H.-M., Kallwellis, V. (2004): Performance analysis of a novel
desiccant and evaporative cooling cycle, Proc. HPC2004, Lacarna, October 11-13,
Greece.
[162] Motta, M., Henning, H.-M. (2005): A novel high efficient sorption system for air
dehumidification (ECOS). Proc. International Sorption Heat Pump Conference, Denver,
June 22-24.
page 61