Objective
To design and install a heat pump capable of recovering heat from the vapour in a catering type dishwasher and to measure, for comparison, the performance and energy consumption of a conventional type dishwasher and the same dishwasher equipped with the heat pump. Energy savings of 45 to 50% were envisaged.
The heat pump system was monitored during 250 working days. Some failures occured (faults in water filling, heating rods destroyed and measurement failures). Annual energy savings were calculated at 2.5 operating hours per day with 35 172 KWh electric (42%) and 550 m3 in global water consumption. The capital payback period for a mass produced machine would be in the order of 6 years, but could be reduced to 3,5 years at a daily operating of 5 hours. Bonnet has not filed any patent. No immediate sale is considered in view of the relatively long capital payback periods. Further development is envisaged. Instead of an air-water heat pump a water-water heat pump is possible (water inlet temp. 55 deg C, outlet 85 deg C). Such a solution would no longer require an electric boiler for heating the rinsing water.
The heat pump system had to be dismantled because the customer did not want to keep it due to the lack of qualified staff.
The heat pump system consists of an evaporator placed at the outlet in the upper part of the machine, using as heat source the exhausted air-water mixture close to the point where it is produced, and two compressors and condensers under the machine. Two small hermetic maneurop type MT80 HT compressors (7.5 Kw unit power) where selected, with a view to low noise level, and the possible use of R12 in the condensing phase, at 75 C. The system includes two parallel running circuits, one to heat washing water, the other to preheat rinsing water. A maximum water temperature of 65 C can be reached by the heat pump, for the difference up to 85 C for rinsing an electrical boiler is foreseen.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
69653 VILLEFRANCHE-SUR-SAONE
France