In a chemical heat pump a substance is used which within the temperature range for which the heat pump is intended has a transition between a solid phase and a solution phase. The substance can for a solar driven chemical heat pump comprise magnesium chloride hexahydrate. In an accumulator part of the heat pump a heat exchanger (21) is provided enclosed by a net (23). The solid phase is primarily located inside the net in contact with the heat exchanger while the solution phase flows out of the net and is collected in a space (24') below the heat exchanger. From this space the solution phase is pumped and sprayed over the heat exchanger from a spray bar (25). Thereby, all the time the equilibrium between the solution phase and the solid phase is maintained. The advantage including the constant temperature step ( DELTA T) and the relatively large energy content of solid substances is thereby combined with the high power of liquid substances. Such a chemical heat pump is among other things suitable for converting low grade heat energy such as solar energy to cooling and in some cases also for a simultaneous production of heat.
