IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask C1 Report, 31 October 2010
Lowenstein [86] presented the applications of LDS coupled with cooling processes that can
be used for:
● comfort air-conditioning in offices, public and residential buildings
● warehouses and production halls for preservation and archiving purposes
● condensation protection to prevent mould and rust destruction from equipment
● production processes e.g. in the food production, pharmaceutical production, semiconductor
production, rubber industry, confectioneries.
The air stream from the absorber can be used directly for:
● high efficiency heat recovery and indirect air heating in low energy buildings, Kerskes [92]
● low temperature drying of agricultural goods and industrial products (“gentle drying”), Rane
[93]
● high efficiency heat recovery and humidity control for indoor swimming pools and
greenhouses, Waldenmaier [94].
4.4 Technology status
In the last years, significant progress has been made in the basic components of desiccant
technology. These include:
4.4.1 Desiccant materials
The behaviour of all desiccant system components is profoundly influenced by the operating
characteristics of the desiccant materials they contain. Recognizing this fact, research
institutions and manufacturers have focused on material science to develop desiccants which
are especially suited to air-conditioning applications.
These efforts have had two primary goals; to develop desiccants which:
1. Use less energy for reactivation and therefore need less energy for cooling
2. Are more stable and fault-tolerant and therefore require less maintenance
Al-Farayedhi et al. [95] listed several important considerations in choosing or designing the
optimal liquid desiccant solution for a dehumidification application:
• High vapor pressure of water in solution
• Low vapor pressure of solute
• Performance of solution steady over large concentration range
• Non-corrosive and chemically stable
• Low viscosity
• High solubility
• Low regeneration temperature
• Non-toxic, harmless
• Low cost
Lithium chloride (LiCl), Calcium Chloride (CaCl2), Lithium Bromide (LiBr), and tri-ethylene
glycol (TEG) are common liquid desiccant materials meeting the above performance
characteristics to varying degrees. LiCl and CaCl2 dominate the most recent research efforts
into liquid desiccant dehumidification systems. Wimby and Berntsson [96] investigated
aqueous solutions of various desiccants, including LiCl and CaCl2, producing experimental
data of density as a function of temperature and mass fraction. This data is of critical
importance when experimenting with liquid desiccant materials, providing concentration as a
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