Heat Recovery

C. MOller/K. Schwarzer/ E. Vieira da Silva*/ C. Mertes
Solar-Institut JOlich / *Universidade Federal do Ceara
Heinrich-Mussmann-Str.5, 52428 JOlich
Tel.: (0049-2461) 99 35 42, Fax: (0049-2461) 99 35 70
E-Mail: c. mueller@sij. fh-aachen. de,

Internet: http://www. sij. fh-aachen. de

1. Introduction

During the thermal desalination of sea water, the evaporation process has a high energy demand. Around 2294 kJ/kg are required to produce just one litre of distilled water. If solar energy is used to power this process a large area is required. Due to the extensive installation required this involves high costs. To make such an idea economically viable, energy-saving desalination technology must be used. An improvement in energy efficiency is possible because of the recovery of the evaporation enthalpy in a multi-layer arrangement (see Figure 1). The main benefit of the development described here is that it is easy to use and avoids the use of moving components such as pumps and electronic controls. The unit also does not need an electricity supply and can be operated by users with little technical skills. This system should provide an economically attractive alternative to the technically demanding desalination systems commercially available, while still producing between 50 and 5000 litres of drinking water per day. The basis of the multi-layer desalination plant was researched as part of an AIF Research Project (FKZ:1708499). Using a seven-layer unit, an energy recovery level of GOR= 2,8 was achieved with a production rate of 8 kg/m2h.

Fig. 1: Schematic of a solar multi-layer desalination unit