Junior research group „Energy-Efficient Liquid Desiccant Hybrid Air-Conditioning Systems

Short Description

The research group investigates and develops energy-efficient hybrid air-conditioning systems in the building sector. In today’s conventional air-conditioning systems with a vapour compression system the dehumidification of the air is realised by cooling the air below the water dew-point of the supply air. As a result the air needs to be reheated after dehumidification before entering the rooms. The dehumidification and reheating of the air in such conventional air-conditioning systems is highly energy-consuming.

The idea of the hybrid systems to be investigated is to separate the dehumidification process of the air from the cooling process. This can reduce significantly the electricity demand for the air-conditioning. Such hybrid systems will be realized by the combination of an open absorption process with a cooling unit. The cooling unit consists of a simple vapour compression system and the dehumidification of the air takes place in the absorber of the open absorption system with a hygroscopic liquid as the desiccant. After the absorption process the liquid desiccant has to be enriched again in a regenerator by adding low temperature heat. The heat for the regeneration can be provided either by waste heat from the condenser or/and from a solar thermal system depending on the climatic conditions and the system design. Such a liquid desiccant hybrid system might have a high potential for the reduction in energy demand in the building sector especially in subtropical regions where the climate is warm, humid, and offers an excellent annual utilization rate.

The general research questions of the group are if it is technical, economical and from an energy point of view worthwhile to combine an open absorption system with a conventional cooling unit like a vapour compression system. For this reason different hybrid system designs will be investigated by a detailed system model both on a stationary and as well on an annual view. This includes the consideration of various climatic conditions and different economic assumptions for electricity costs. In addition an experimental unit which represents a variable liquid desiccant hybrid system will be designed and constructed with the aim to verify the modelled data.

Duration

10.2015 until 09.2017

Contact

Daniel Fleig

Lisa Mucke

Financing

Kassel University