Coupled orc heat pump electric generator system

A coupled industrial heat pump (IHP)/organic Rankine cycle (ORC) power generation system comprising:

• (a) a stack of multiple IHPs connected in series, the stack configured to maximize its net coefficient of performance, defined as a total thermal energy output of the stack divided by a total electric energy input to the stack, each of the multiple IHPs including:
• a first evaporator operative to transfer heat from a stream of a source water to a first refrigerant, thereby vaporizing the first refrigerant isothermally from a liquid state to a vapor state at a specified first evaporator pressure, while reducing the source water from an inlet temperature to an outlet temperature;
• a compressor coupled to the first evaporator and operative to receive the first refrigerant in its vapor state from the first evaporator and compress it to a compressor pressure at a compressor temperature;
• a first condenser coupled to the compressor and operative to receive the first refrigerant leaving the compressor in a compressed condition in its vapor state and to transfer the heat from the first refrigerant to a sink heat transfer fluid, thereby raising the sink heat transfer fluid from a first sink temperature to a second sink temperature and causing the first refrigerant to condense to its liquid state;
• and
• a flashing liquid expander containing a first turboexpander, the flashing liquid expander fluidly communicating with the first condenser and with the first evaporator, wherein the flashing liquid expander is operative to accommodate the first refrigerant in its liquid state as it is passed at constant enthalpy to the first evaporator at the first evaporator pressure and a first evaporator temperature;
• wherein a sum of a temperature increase imparted to the sink heat transfer fluid by each of the multiple IHPs is a temperature rise determined for a specified external thermal load and does not exceed a maximum total temperature rise of 150° F., thereby limiting thermal loads of each of the multiple IHPs;
• wherein each of the multiple IHPs is connected to a reservoir or a manifold having an incoming flow of the source water, modulating the incoming flow to each of the multiple IHPs to maintain a specified temperature drop of the source water as it passes through the first evaporator,
• wherein the temperature rise in each of the multiple IHPs is disproportionately allocated such that, relative to that of other of the multiple IHPs, if the second sink temperature is low, a lift is small, and a COP is high, a temperature increase allocated to the IHP is high and if the second sink temperature is high, the lift is large, and the COP is low, the temperature increase allocated to the IHP is low;
• and
• (b) an organic Rankine cycle generator coupled to the multiple IHPs, the organic Rankine cycle generator having:
• a second evaporator configured to receive the sink heat transfer fluid at a sink outlet temperature from the stack and operative to transfer the heat from the sink heat transfer fluid to a second refrigerant, vaporizing the second refrigerant from its liquid state to its vapor state;
• a second turboexpander configured to receive the second refrigerant from the second evaporator and operative to generate electricity;
• a second condenser configured to receive the second refrigerant leaving the second turboexpander and operative to condense the second refrigerant from its vapor state to its liquid state;
• a condensate receiving tank coupled to the second condenser and operative to collect the second refrigerant in its liquid state;
• and
• a feed pump coupled to the condensate receiving tank, operative to extract, pressurize, and deliver the second refrigerant to the second evaporator at a second evaporator pressure;
• wherein the stack and the second evaporator of the ORC are configured to circulate the sink heat transfer fluid in a closed loop, sequentially through each of the multiple IHPs and through the second evaporator the flashing liquid expander utilizes a difference between a first condenser pressure and the first evaporator pressure to drive the first turboexpander, thereby generating additional electricity and reducing an electricity draw from an electric output of the ORC.

A method of power generation, comprising:

• providing a plurality of industrial heat pumps (IHPs) and an organic Rankine cycle generator (ORC) having an ORC evaporator and an ORC turboexpander;
• circulating a sink heat transfer fluid through each of the plurality of IHPs in series and through the ORC evaporator;
• feeding a source water to each of the plurality of IHPs;
• transferring heat from the source water to the sink heat transfer fluid in each of the plurality of IHPs;
• circulating an ORC refrigerant through the ORC evaporator and the ORC turboexpander;
• transferring the heat from the sink heat transfer fluid to the ORC refrigerant via the ORC evaporator;
• returning the sink heat transfer fluid to the plurality of IHPs;
• generating electricity by passing the ORC refrigerant through the ORC turboexpander;
• routing a first portion of the electricity to the plurality of IHPs;
• and
• exporting a second portion of the electricity.