Apparatus and method for generating power and refrigeration from low-grade heat

An apparatus for utilizing low-grade heat including:

• a heating module including:
• a boiler;
• and
• a heat source for energizing the boiler to vaporize liquid working fluid to high-temperature and high-pressure gaseous state;
• a power generator module including:
• an expansion turbine of which an inlet is connected to an outlet of the boiler;
• and
• a power generator coupled to the expansion turbine so that the high-temperature and high-pressure gaseous working fluid leaves from the boiler into the expansion turbine and drives the power generator for generating electricity wherein, after traveling through the expansion turbine, the working fluid becomes medium-temperature and medium-pressure gaseous working fluid;
• a low-temperature evaporator in which liquid working fluid absorbs heat, vaporizes, provides refrigeration, and becomes low-pressure gaseous working fluid;
• an ejector including a nozzle, a mixing section, a constant area section, a diffuser section, a suction port, an inlet and an outlet, wherein the inlet is connected to an outlet of the expansion turbine so that the medium-temperature and medium-pressure gaseous working fluid leaves from the expansion turbine and enters the ejector inlet to accelerate and become a low-pressure supersonic stream at the nozzle where the low-pressure supersonic stream then produces a high vacuum at the mixing section and sucks the low-pressure gaseous working fluid from the low-temperature evaporator through the suction port where the two streams mix together and become a supersonic mixed stream at the mixing section, and then enter the constant area section where, when going through the constant area section, a normal shock wave occurs, accompanied by a pressure where, after the shock, the velocity of the mixed stream becomes subsonic and decelerated at the diffuser section, and then out of the ejector outlet wherein, the ejector acts as a thermally derived gas compressor that utilizes medium pressure vaporized working fluid to compress low pressure gas, and is reliable for not containing any mechanical parts;
• a pressure pump;
• a heat exchanger comprising a hot channel of which an inlet thereof is connected to the ejector and a cold channel of which an inlet thereof is connected to the pressure pump such that the residual heat of the working fluid out of the ejector is recovered by preheating the liquid working fluid out of the pressure pump so that loads on the heating module and a condenser module are reduced, respectively;
• the condenser module including:
• an inlet of a condenser connected to a hot channel outlet of the heat exchanger so that the gaseous working fluid enters the inlet of the condenser through the hot channel of the heat exchanger, wherein an outlet of the condenser is connected to the low-temperature evaporator through a throttle so that a portion of the liquid working fluid selectively leaves from the condenser to the low-temperature evaporator;
• and
• a cooling tower for cycling a coolant through the condenser for condensing the gaseous working fluid to liquid working fluid;
• a reservoir connected to the condenser so that the reservoir receives any portion of the liquid working fluid from the condenser module not selectively directed to the low-temperature evaporator and contains the same;
• wherein the pressure pump is connected to the reservoir so that the ejector provides medium-pressure gaseous working fluid to preheat the liquid working fluid traveling from the pressure pump to reduce burdens on the heating module and the condenser module, wherein the pump is further connected to the heat exchanger so that while traveling to the boiler through the heat exchanger, the liquid working fluid gets heated and vaporized;
• a first direction controllable three-way valve provided between the boiler and the expansion turbine;
• and
• a second direction controllable three-way valve provided between the expansion turbine and the ejector, wherein the operation method of the apparatus is that the first and second direction controllable three-way valves, are operable to direct the working fluid in a selected one of various directions for executing all of a power generation and refrigeration mode, a refrigeration mode, a power generation mode, and an idle mode.