Development of dishwashers with low energy consumption

In connection with this application a number of experiments have been made where a plate with burned egg has been boiled under vacuum at 45 deg. C. The tests show that a bubble effect occurs close to the dirt, which loosens it. The principle of vacuum may be used in combination with cleaning the liquid in the vacuum tank and reusing it a certain number of times. Thus it is possible to minimize the waste of water and to utilize the heat content of the liquid. By using a 2-chamber container tank the process may be described thus: The tableware is put into chamber 1 where it is rinsed in cold water. At the same time the liquid for the vacuum process is in chamber 2 where grease etc. will float onto the surface and may be removed. After the rinsing the cold water is carried off in the drain (outlet) and the vacuum liquid is led into chamber 1. Vacuum is pumped so that the pressure is 0,1 bar. By a pressure of 0,1 bar and 45 deg. C a bubble effect occurs which works on the surface of the tableware. After the vacuum process the liquid is led through filtering etc. into chamber 2. Here the tableware is rinsed in hot water which is subjected to heat recovery after which the tableware will dry/- the water evaporates and the process can start all over again. Whether or not the principle may be applied to household machines will be looked into in the long term. Industrial dishwashing machines typically let out 15 litres of water at 60 deg. C per wash into the drain. The composition of the discharge water entails that special demands are made on a heat exchanger if the problem of clogging up is to be avoided. A heat exchanger with a high efficiency is selected and tested