FAN COOLED ABSORPTION REFRIGERATING APPARATUS

Abstract: In an absorption refrigerating apparatus (18) operated by a fuel in gas or liquid state the condenser (50) is cooled by an air flow generated by a fan (82). The fan is driven by a heat operated motor consisting of an endless thread- or band- formed means (84) of a shape memory alloy which gets its operating heat from the exhaust gas from the fuel.

Description: The invention relates to an absorption refrigerating apparatus comprising a boiler heated by gaseous or liquid fuel, a condenser and a fan generating an air stream to cool the condenser. An absorption refrigerating apparatus is known through e.g. GB patent No. 402,298, where among other things the condenser of the apparatus is cooled by a fan which increases the refrigerating power of the apparatus. At the known apparatus the fan is operated by electricity which is, however, not always available. The object of the invention is to bring about such an absorption refrigerating apparatus introductorily set forth, where the fan can be operated independently of electricity by the heat from the exhaust gas from the fuel. This object is reached through the absorption refrigerating apparatus according to the invention by a heat operated motor driving the fan, the motor comprising a first wheel heated by the exhaust gas from the fuel, a second wheel driving the fan and an endless thread- or band-shaped material passing around the first and second wheel and consisting of a shape memory alloy having the tendency to straighten our when heated by contact with the first wheel. Such a motor is known per se through e.g. U.S. patent No. 4,275,561. One embodiment of an absorption refrigerating apparatus according to the invention will be described below in connection with the attached drawing, in which Fig. 1 schematically shows an absorption refrigerating apparatus with a fan cooling the condenser of the apparatus and Fig. 2 in a sectional view according to the marking II-II of Fig. 1 shows the driving of the fan by an endless thread of a shape memory alloy. Numeral 10 designates a refrigerator cabinet containing a refrigerated hamber 12 which is closed by a door 14. The chamber 12 is cooled by the evaporator 16 of an absorption refrigerating apparatus 18 arranged behind the cabinet 10. The refrigerating apparatus 18, which is of a known kind, e.g. according to Fig. 3 of U.S. patent No. 4,691,529, shows an absorber vessel 32 containing an absorption liquid, such as water, in which a refrigerant, such as ammonia, is dissolved. This solution, which is relatively rich in refrigerant, is called a rich solution. The rich solution exits from the absorber vessel 32 through a conduit 34 and enters a boiler 36 in which the rich solution is supplied with a heat from a gas burner 38. Refrigerant vapor boils off from the rich solution which thereby becomes a so-called weak solution. The mixture of refrigerant vapor and weak solution is expelled through a pump pipe 42, the refrigerant vapor continuing to a separator 44 which separates out absorption liquid accompanying the refrigerant vapor and the weak solution being collected in an outer pipe 46 of the boiler 36 to a certain level 48. The refrigerant vapor flows from the separator 44 into a condenser 50, where heat is transferred from the vapor to the surrounding air so that the vapor condenses. The refrigerant condensate leaves the condenser through a conduit 52 and enters the evaporator 16, where the condensate meets a flow of an inert gas, such as hydrogen gas, and is vaporized in an outer pipe 54 in the inert gas during absorption of heat from the chamber 12. The inert gas is supplied to the evaporator 16 through an inner pipe 56 which is located within the outer pipe 54 and the mixture of inert gas and vaporized refrigerant exits from the evaporator 16 through the pipe 54 and continues via a pipe 58 to the absorber vessel 32. From the absorber vessel 32, the mixture of refrigerant vapor and inert gas is elevated through an absorber 60 and meets the weak solution, which, driven by the level 48, comes from the pipe 46 via a conduit 62 into the upper part of the absorber 60 at 64. While flowing downwards through the absorber 60, the weak solution absorbs refrigerant vapor flowing upwards during rejecting of heat to the surrounding air, the weak solution thereby becoming a rich solution again before it flows down into the absorber vessel 32 at 66. The elevating inert gas continues from the absorber 60 to the pipe 56 and enters into the evaporator 16 and permits the refrigerant condensate to vaporize in it. In order to prevent refrigerant vapor, which possibly does not condensate in the condenser, from collecting in the condenser and blocking the outflow of refrigerant condensate from the condenser, a vent conduit 68 is arranged between the outlet of the condenser 50 and the conduit 58, which conduit 68 leads gaseous medium to the absorber vessel 32. The burner 38 operates the boiler 36 via a pipe 70, through which the hot exhaust gas from the burner passes. The pipe 70 is prolonged by a pipe 72 which is rotatably journalled on the pipe 70 around an axis 76 by means of a bearing 74. A wheel 78 is fastened to the pipe 72. An other wheel 80 is journalled rotatably below the condenser 50. The wheel 80 is provided with fan blades 82 inside its circumference. The wheels 78 and 80 are connected by an endless thread 84 of a shape memory alloy, e.g. of nickel and titanium, which is such that the thread 84 at a certain higher temperature strives to straighten out. Through heat transfer from the exhaust gas via the pipe 72 and the wheel 78, the part of the thread 84, which is in contact with the wheel 78, reaches the higher temperature. Other parts of the thread 84 are cooled by the surrounding air to a lower temperature which is lower than said higher temperature. By this the thread 84 can bring the wheels 78 and 80 to rotate. Such a motor is described in e.g. the previously cited U.S. patent No. 4,275,561. The wheel 80 brings the fan blades 82 with it which causes a forced air circulation past the condenser 50, the cooling of which thereby becoming improved resulting in an increase of the refrigerating power of the absorption refrigerating apparatus.

Claims: Absorption refrigerating apparatus (18) comprising a boiler (36) heated by gaseous or liquid fuel, a condenser (50) and a fan (82) generating an air stream to cool the condenser (50), characterized by a heat operated motor (78,80,84) driving the fan (82), the motor comprising a first wheel (78) heated by the exhaust gas from the fuel, a second wheel (80) driving the fan and an endless thread - or band -shaped material (84) passing around the first and second wheel (78,80) and consisting of a shape memory alloy having the tendency to straighten out when heated by contact with the first wheel (78). Absorption refrigerating apparatus according to claim 1, characterized in that the material (84) gets its operating heat from the first wheel (78) which is heated by exhaust gas passing through this wheel (78). Absorption refrigerating apparatus according to claim 1 or 2, characterized in that the fan consists of fan blades (82) arranged in the second wheel (80) inside its circumference.

Inventors: BLOMBERG, PETER ERIK
Applicants: AKTIEBOLAGET ELECTROLUX
Application year: 1989
Main classification: F25B15
IPC codes: F03G7, F25B15, F25D23, F25D11