Abstract: An absorption refrigeration unit having a purge system that will sense when the discharge pressure of the solution pump becomes subatmospheric and will automatically increase the speed of the pump to bring the discharge pressure up to a desired level above atmospheric pressure so that a purging cycle can be achieved. The system further monitors the generation solution level and interrupts the purging cycle in the event the solution reaches an undesirable level.

Abstract: A multi-stage absorption refrigeration system having an upper stage that includes a generator and condenser that operate at above atmospheric pressure and a lower stage that includes a generator and a condenser that operates at or near atmospheric pressure. The upper stage condenser is placed in heat transfer relation with the lower stage generator to produce refrigerant vapor from solution contained in the lower stage generator. A water condenser is connected to the lower stage generator so that vapor produced in the lower stage generator can be used to heat hot water or other fluid. When the system is placed in a water heating mode, the flow of solution is terminated to the upper stage generator and condensate leaving the upper stage condenser is circulated back through the upper stage generator.

Abstract: An over-concentration control system for use with an absorption machine of the type having either a single, double and triple effect cooling and heating cycle, which uses lithium bromide in solution with water as the operating liquid. The operating liquid being characterized by a concentration indicative of the quantity of lithium bromide dissolved in water, and by a phase diagram having a crystallization boundary that defines the combinations of concentration and temperature which correspond to a condition of saturation in the solution. A sensing means is provided at a predetermined location within the system which is responsive to the depth of said solution for generating a concentration signal indicative of the concentration of the liquid. A temperature sensor is also provided for generating a temperature signal indicative of the temperature of the liquid.