Thermally Enhanced Cascade Cooling System

Abstract

A cascade cooling system that uses low-grade thermal and other energy input sources to provide refrigeration and air conditioning in stationary and mobile applications. A two-loop embodiment includes a heat-powered first loop incorporating a vapor-jet compressor and a second loop based on a mechanical compressor powered by an electric motor or other source of rotational torque. The system uses waste heat, solar thermal or a fuel-fired heat source to partially or fully offset mechanical/electrical energy input. The system can also operate entirely on thermal, electrical or mechanical input. The ability to use multiple energy sources in any combination maximizes energy efficiency, performance and reliability. The system is well suited to making beneficial use of waste heat in vehicle applications. In stationary applications, solar thermal and/or waste heat from industrial processes can be used to improve the efficiency of conventional cooling systems.

1 . A cascade cooling system comprising;
 a source of thermal energy and,   a primary cooling loop including;
 a mechanical compression means which uses mechanical energy to compress a refrigerant gas from an evaporator pressure to a condensing pressure and, 
 an evaporator located to cool a compartment by using heat from the compartment to evaporate a liquid refrigerant and, 
 a refrigerant flow regulator to create a differential pressure and to regulate the flow of liquid refrigerant into the said evaporator 
 a condenser in thermal communication with an evaporator of an ejector boosting loop such that heat from the primary cooling loop is transferred to the ejector boosting loop and, 
   an ejector boosting loop comprising;
 a boiler in which heat from said source of thermal energy converts a motive refrigerant from a liquid state to a vapor having a motive pressure and motive temperature and, 
 a refrigerant flow regulator to receive and regulate the flow of a portion of the said motive refrigerant into an evaporator, the said evaporator in thermal communication with, and operably positioned to receive heat from, the said primary cooling loop condenser and, 
 an ejector compression means having a high pressure port, a low pressure port and a discharge port and a venturi mixing chamber and further configured to receive the said vapor at a motive pressure and temperature in the high pressure port, and to further receive refrigerant vapor from the said evaporator in the low pressure port and to mix and discharge vapor out the discharge port and, 
 a condenser located to transfer heat from the vapor exiting the discharge port of the ejector compression means, to an area outside the compartment to be cooled and, 
   wherein the operation of the ejector boosting loop improves the energy efficiency of the primary cooling loop by reducing the pressure differential imposed on the mechanical compression means.   
     
     
         2 . The system of  claim 1  which further includes an electric motor operably coupled to provide motive power to the said mechanical compression means. 
     
     
         3 . The system of  claim 2  in which the electric motor receives electric power from one or more of a listing including electric storage battery, fuel cell, photovoltaic solar panel, wind-powered generator, engine-driven generator, or utility power grid. 
     
     
         4 . The system of  claim 2  wherein the electric motor is a variable-speed motor. 
     
     
         5 . The system of  claim 1  wherein the said source of thermal energy may be a plurality of sources. 
     
     
         6 . The system of  claim 5  wherein the said plurality of sources includes one or more of an internal combustion engine cooling system, heated gas from a combusted fuel, a fuel-fired heater, a solar thermal collector, an electric propulsion motor, motor control electronic components, an electro-chemical process, a chemical process, a geothermal source, biofuel combustion, or the thermal byproduct of electric power generation. 
     
     
         7 . The system of  claim 1  which further includes an intelligent control system which adjusts the rotational speed of various motors and the position of various valves to maximize the performance and efficiency of the system. 
     
     
         8 . The system of  claim 1  wherein the cooled compartment is the cabin of a vehicle. 
     
     
         9 . The system of  claim 1  wherein the cooled compartment is a building. 
     
     
         10 . The system of  claim 1  wherein the cooled compartment is used for holding one or more items from a list including food, chemicals, plants or animals. 
     
     
         11 . The system of  claim 1  wherein the cooled compartment is an enclosure for a chemical or electrical process. 
     
     
         12 . The system of  claim 1  wherein the cooled compartment is a plurality of compartments. 
     
     
         13 . A three-loop heat transfer system comprising;
 a heat input loop including;
 a source of input heat energy and, 
 a fluid path including heat transfer liquid and, 
 a pump positioned to circulate the heat transfer liquid so as to transfer heat energy from the said source of input heat to a boiler and, 
   an ejector cooling loop including,
 a boiler in thermal communication with the heat input loop which boils a liquid refrigerant in an ejector cooling loop to create a vapor at a motive pressure and motive temperature and, 
 an ejector compressor which, operating on the venturi principle, uses the said vapor at a motive pressure and motive temperature to create a low pressure zone and, 
 a condenser which condenses the refrigerant vapor exiting the ejector compressor by transferring heat from the vapor to an area outside a cooled compartment and, 
 a liquid pressure pump which receives liquid refrigerant from the condenser and circulates it to the said boiler and to an evaporator. 
 an evaporator in fluid communication with the said low pressure zone of the ejector compressor and, in thermal communication with the said primary cooling loop, such that the low pressure causes liquid refrigerant to be evaporated thereby absorbing heat from the primary cooling loop and, 
   a primary cooling loop including,
 a gas compressor receiving input energy from a rotating shaft and, 
 a condenser in thermal communication with the said evaporator in an ejector cooling loop such that, heat in the vapor discharged from the said gas compressor is transferred to refrigerant in the ejector cooling loop thereby vaporizing refrigerant in the ejector cooling loop and liquefying refrigerant in the primary cooling loop and, 
 an evaporator positioned to receive liquid refrigerant from the condenser and boil it to a vapor by extracting heat from a compartment to be cooled. 
   
     
     
         14 . The system of  claim 13  which the evaporator in the primary cooling loop is a refrigerant-liquid heat exchanger positioned to remove heat from a liquid cooling loop comprising;
 a fluid circuit containing a liquid heat transfer fluid and, 
 a heat exchanger positioned to transfer heat from a compartment to be cooled to the said liquid heat transfer fluid. 
 
     
     
         15 . The system of  claim 13  in which the said primary cooling loop is a plurality of cooling loops. 
     
     
         16 . The system of  claim 15  in which one or more of the compartments to be cooled is a vehicle operator cabin, a vehicle sleeping cabin or the cargo area of a vehicle. 
     
     
         17 . The system of  claim 13  in which the mechanical compressor is driven by an internal combustion engine. 
     
     
         18 . The system of  claim 13  in which the mechanical compressor is driven by an electric motor. 
     
     
         19 . A heat-powered cooling system comprising;
 a first cooling circuit including;
 a mechanical refrigerant compressor operably coupled to a vapor expander, said vapor expander receiving a portion of vaporized refrigerant at a first motive pressure from the boiler of a second cooling circuit, 
 a first refrigerant evaporator which cools the air in a compartment by vaporizing a liquid refrigerant, 
 a first refrigerant condenser which transfers heat from the refrigerant of the first cooling circuit to a second cooling circuit, 
   a second cooling circuit including;
 a venturi ejector compressor which accelerates a portion of the said vaporized refrigerant at a first motive pressure through a nozzle and discharges it to a condenser at a lower second pressure such that a vacuum region at a lowest third pressure is created, 
 a second refrigerant evaporator in thermal communication with the said first refrigerant evaporator, which receives liquid refrigerant from a second refrigerant condenser and evaporates it at the said third pressure using heat extracted from the refrigerant of the said first cooling circuit, 
 a second condenser operably positioned to liquify and cool vaporized refrigerant by transferring heat to an exterior heat sink, 
 a liquid refrigerant pump in fluid communication with the second condenser and a refrigerant boiler. 
 a refrigerant boiler which, upon receiving heat energy from an external heat source, boils liquid refrigerant to create the said vapor at a first motive pressure such that, 
   thermal energy input into the second cooling circuit cools the condenser of the first cooling circuit and thereby reduces the amount of energy required by the mechanical refrigerant compressor.   
     
     
         20 . The system of  claim 19  in which the said mechanical compressor is a variable-speed compressor. 
     
     
         21 . The system of  claim 19  which further includes an electric rotating machine operably coupled to the said mechanical refrigerant compressor and vapor expander. 
     
     
         22 . The system of  claim 21  in which the electric rotating machine is a motor/generator. 
     
     
         23 . The system of  claim 22  in which the motor/generator uses some or all of the electrical output energy from a generating mode to fulfill the electrical power demand from system controls and other devices. 
     
     
         24 . The system of  claim 22  in which the motor/generator uses some or all of the electrical output energy from a generating mode to charge an electric energy storage device. 
     
     
         25 . The system of  claim 22  which further includes a plurality of electrically configurable flow control valves operably positioned and configurable so as to bypass the said ejector compressor in the ejector cooling loop and further including such refrigerant flow controls as required to enable the said vapor expander to function as a compressor when powered by the said motor/generator. 
     
     
         26 . The system of  claim 22  which further includes an intelligent control system which adjusts various operational parameters of the systems to identify and optimally use energy input sources according to a predetermined priority or preference. 
     
     
         27 . The system of  claim 26  in which the intelligent control system adjusts various operational parameters of the systems to optimize system efficiency. 
     
     
         28 . The system of  claim 26  in which the intelligent control system further adjusts various operational parameters based partially or entirely on stored historical operational data from previous run cycles. 
     
     
         29 . The system of  claim 26  in which the intelligent control system adjusts the priority of energy input sources or other operational parameters based on information received through sensors or determined by real-time calculations. 
     
     
         30 . The system of  claim 26  in which the intelligent control system adjusts the priority of energy input sources or other operational parameters based on received data which has been transmitted from external sources. 
     
     
         31 . The system of  claim 26  in which the said operational parameters include one or more from a list including flow control position, valve timing, valve opening, condenser temperature, evaporator temperature condensing fan speed, evaporator fan speed, motor input voltage, motor commutation, generator output voltage, generator load, liquid pump speed, compressor capacity, vapor expander capacity, flow of motive vapor to the expander, flow of motive vapor to the ejector compressor, boiler temperature, and cooling capacity.