Gas engine driven heat pump system with integrated heat recovery and energy saving subsystems

Abstract

A gas heat pump system powered by natural gas, propane or similar gaseous fuel is disclosed. The system uses heat recovery and heat addition to manage efficient heating and cooling cycles. In a cooling cycle excess heat is vented to the atmosphere while in a heating cycle, excess heat is used to heat a subject structure and to prevent frost from forming on outdoor heat exchangers. A control system monitors the system's operation and corrects abnormal operational conditions or shuts down the system until the system can be manually inspected. The costs of system operation are less than electric systems because of the efficiencies and use of natural gas or propane.

1 . A method of utilizing a system to generate heated or cooled air for supply to a subject structure comprising:
 supplying pressure-regulated a gaseous fuel to an engine and optional auxiliary heater;   directing engine combustion air through an air cooler device, filter and then into an air-fuel mixture device operable to mix the natural gas or propane with the combustion air;   directing refrigerant through indoor or outdoor heat exchangers depending on whether the system is in a heating or cooling cycle;   directing coolant through said engine such that coolant temperature is raised by waste heat;   when in a cooling cycle:
 directing coolant from the engine to an engine temperature control valve that directs the coolant to a radiator that dispenses any excess heat; 
   when in a heating cycle:
 determining an ambient temperature; 
 if the ambient temperature is below a threshold frost point temperature, directing the engine coolant from the engine to a frost avoidance valve that directs the coolant to outdoor heat exchangers; and 
 if the ambient temperature is above a threshold frost point temperature, directing the engine coolant from the engine to an indoor heat exchanger. 
   
   
   
       2 . The method of  claim 1  further comprising directing, during the cooling cycle, engine coolant to a hot water exchanger operable to heat a domestic water source. 
   
   
       3 . The method of  claim 1  further comprising utilizing a pool or hot water heater as the domestic water source. 
   
   
       4 . The method of  claim 1  further comprising adding heat, during the heating cycle, to the coolant between the engine and the engine temperature control valve. 
   
   
       5 . The method of  claim 1  further comprising directing all coolant to the engine at engine start-up until the engine reaches a desired operating temperature. 
   
   
       6 . The method of  claim 1  further comprising utilizing natural gas or propane as the gaseous fuel. 
   
   
       7 . A method of utilizing a system to generate heated or cooled air for supply to a subject structure comprising:
 supplying pressure-regulated natural gas or propane to an engine and optional auxiliary heater;   directing engine combustion air through an air cooler device, filter and then into an air-fuel mixture device operable to mix the natural gas or propane with the combustion air;   directing refrigerant through indoor or outdoor heat exchangers depending on whether the system is in a heating or cooling cycle;   directing coolant through said engine such that coolant temperature is raised by waste heat;   when in a cooling cycle:
 directing coolant from the engine to an engine temperature control valve that directs the coolant to a radiator that dispenses any excess heat; 
   when in a heating cycle:
 determining an ambient temperature; 
 if the ambient temperature is below a threshold frost point temperature, directing the engine coolant from the engine to a frost avoidance valve that directs the coolant to outdoor heat exchangers; 
 if the ambient temperature is above a threshold frost point temperature, directing the engine coolant from the engine to an indoor heat exchanger; and 
   varying engine speed, number of refrigeration compressors running and blower speed in response to a thermostat setting.   
   
   
       8 . The method of  claim 7  further comprising directing, during the cooling cycle, engine coolant to a hot water exchanger operable to heat a domestic water source. 
   
   
       9 . The method of  claim 8  further comprising utilizing a pool or hot water heater as the domestic water source. 
   
   
       10 . The method of  claim 8  further comprising adding heat, during the heating cycle, to the coolant between the engine and the engine temperature control valve. 
   
   
       11 . The method of  claim 8  further comprising directing all coolant to the engine at engine start-up until the engine reaches a desired operating temperature. 
   
   
       12 . The method of  claim 8  further comprising utilizing a control system for varying engine speed, number of refrigeration compressors running and blower speed in response to a thermostat setting. 
   
   
       13 . A method of utilizing a system to generate heated or cooled air for supply to a subject structure comprising:
 supplying pressure-regulated a gaseous fuel to an engine and optional auxiliary heater;   directing engine combustion air through an air cooler device, filter and then into an air-fuel mixture device operable to mix the natural gas or propane with the combustion air;   directing refrigerant through indoor or outdoor heat exchangers depending on whether the system is in a heating or cooling cycle;   directing coolant through said engine such that coolant temperature is raised by waste heat;   when in a cooling cycle:
 directing coolant from the engine to an engine temperature control valve that directs the coolant to a radiator that dispenses any excess heat; 
 further exchanging water heat from said engine coolant to a domestic water source; and 
   regulating an amount of heat transferred to said domestic water source by diverting a portion of said hot engine coolant;   when in a heating cycle:
 determining an ambient temperature; 
 if the ambient temperature is below a threshold frost point temperature, directing the engine coolant from the engine to a frost avoidance valve that directs the coolant to outdoor heat exchangers; and 
 if the ambient temperature is above a threshold frost point temperature, directing the engine coolant from the engine to an indoor heat exchanger. 
   
   
   
       14 . The method of  claim 13  further comprising utilizing a hot water heat exchanger apparatus to exchange water heat from said engine coolant to a domestic water source during a cooling cycle. 
   
   
       15 . The method of  claim 13  further comprising utilizing a control valve to regulate an amount of heat transferred to said domestic water source by diverting a portion of said hot engine coolant.