Combined heat and power system

• US 9,803,584 B2
• Filed: 04/01/2016
• Issued: 10/31/2017
• Est. Priority Date: 04/01/2015
• Status: Active Grant

• Current Assignee: Briggs & Stratton LLC (Briggs & Stratton Corporation)
• Original Assignee: Briggs & Stratton Corporation
• Inventors: Schmalz, Jacob J.
• Primary Examiner(s): Cuevas, Pedro J
• Application Number:
  US15/089,240
• Publication Number:
  US 20160290281A1
• Time in Patent Office: 578 Days
• Field of Search: 290 1 A, 290 2
• CPC Class Codes: F02B 2043/103 Natural gas, e.g. methane or LNG used as a fuel
• CPC Class Codes: F02B 43/02 Engines characterised by means for increasing operating efficiency
• CPC Class Codes: F02B 63/04 for electric generators
• CPC Class Codes: F02G 5/02 Profiting from waste heat of exhaust gases
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A combined heat and power system includes a liquid-cooled internal combustion engine, an air-cooled alternator, an air-to-water heat exchanger, and a coolant-to water heat exchanger. The liquid-cooled internal combustion engine includes a liquid cooling system configured to cool the engine with coolant thereby heating the coolant. The air-cooled alternator is configured to be driven by the internal combustion engine to produce electricity. The alternator includes an air cooling system configured to cool the alternator thereby heating air. The air-to-water heat exchanger is configured to place heated air and water in a heat exchange relationship to preheat the water and cool the air. The coolant-to-water heat exchanger is configured to place heated coolant and preheated water from the air-to-water heat exchanger in a heat exchange relationship to further heat the water and cool the coolant. The coolant-to-water heat exchanger provides heated water to the housing water outlet.

Claims

1. A combined heat and power system comprising:

a housing including a first chamber, a second chamber, and a passageway fluidly coupling the first chamber to the second chamber;

a coolant circuit including a coolant pump configured to pump coolant through the coolant circuit;

a liquid-cooled internal combustion engine including an exhaust outlet configured to output exhaust at a first exhaust temperature and a liquid cooling system with an engine coolant inlet configured to receive coolant at a first coolant temperature from a first portion of the coolant circuit and an engine coolant outlet configured to output coolant at a second coolant temperature greater than the first coolant temperature to a second portion of the coolant circuit, wherein the engine is located in the first chamber, and wherein the liquid cooling system is configured to cool the engine thereby heating the coolant;

an air-cooled alternator configured to be driven by the internal combustion engine to produce electricity, the alternator including an air cooling system with an alternator air inlet configured to receive air from the second chamber at a first air temperature and an alternator air outlet configured to output air at a second air temperature greater than the first air temperature to the first chamber, wherein the air cooling system is configured to cool the alternator thereby heating the air;

a water circuit including a housing water inlet, a housing water outlet, and a water pump configured to pump water through the water circuit, wherein the housing water inlet is configured to receive water from outside the housing at a first water temperature and the housing water outlet is configured to output water from the housing;

an air-to-water heat exchanger, comprising;

an ATW exchanger air inlet fluidly coupled to the first chamber and configured to receive air from the first chamber at the second air temperature;

an ATW exchanger air outlet fluid coupled to the second chamber and configured to output air to the second chamber at a third air temperature less than second air temperature;

an ATW exchanger water inlet fluidly coupled to a first portion of the water circuit and configured to receive water at the first water temperature; and

an ATW exchanger water outlet fluidly coupled to a second portion of the water circuit and configured to output water at a second water temperature greater than the first water temperature;

wherein the air-to-water heat exchanger is configured to place the air and the water in a heat exchange relationship to heat the water and the cool the air;

a coolant-to-water heat exchanger, comprising;

a CTW exchanger coolant inlet fluidly coupled to the second portion of the coolant circuit and configured to receive coolant at the second coolant temperature;

a CTW exchanger coolant outlet configured to output coolant to a third portion of the coolant circuit at a third coolant temperature less than the second coolant temperature;

a CTW exchanger water inlet fluidly coupled to the second portion of the water circuit and configured to receive water at the second water temperature; and

a CTW exchanger water outlet fluidly coupled to a third portion of the water circuit and configured to output water at a third water temperature greater than the second water temperature;

wherein the coolant-to-water heat exchanger is configured to place the coolant and the water in a heat exchange relationship to heat the water and the cool the coolant; and

wherein the third portion of the water circuit is fluidly coupled to the housing water outlet; and

an exhaust-to-coolant heat exchanger, comprising;

an ETC exchanger exhaust inlet fluidly coupled to the engine exhaust outlet and configured to receive exhaust from the engine at the first exhaust temperature;

an ETC exchanger exhaust outlet configured to output exhaust at a second exhaust temperature less than the first exhaust temperature;

an ETC exchanger coolant inlet fluidly coupled to the third portion of the coolant circuit and configured to receive coolant at the third coolant temperature; and

an ETC exchanger coolant outlet fluidly coupled the first portion of the coolant circuit and configured to output coolant at a fourth coolant temperature greater than the third coolant temperature;

wherein the exhaust-to-coolant heat exchanger is configured to place the exhaust and the coolant in a heat exchange relationship to heat the coolant and cool the exhaust.

2. The combined heat and power system of claim 1, further comprising:

a valve including a valve input fluidly coupled to the third portion of the water circuit, a first valve outlet fluidly coupled to the housing water outlet, and a second valve outlet fluidly coupled to a fourth portion of the water circuit, wherein the valve is operable to output water from either the first valve outlet or the second valve outlet,

wherein the fourth portion of the water circuit is fluidly coupled to the first portion of the water circuit;

a water temperature sensor configured to sense the third water temperature;

a controller configured to operate the valve to output water from the first valve outlet when the third water temperature as sensed by the water temperature sensor is greater than a target water temperature and configured to output water from the second valve outlet when the third water temperature as sensed by the water temperature sensor is less than the target water temperature.

3. The combined heat and power system of claim 2, further comprising:

a variable frequency drive configured to drive the water pump at varying pump speeds;

wherein the controller is further configured to control the variable frequency drive to vary the pump speed of the water pump in response to the third water temperature sensed by the water temperature sensor.

4. The combined heat and power system of claim 1, further comprising:

a variable frequency drive configured to drive the water pump at varying pump speeds;

a water flow sensor configured to sense a water flow rate in the water circuit;

a controller configured to provide a maintenance indicator when the pump speed when the water flow rate sensed by the water flow sensor is below a threshold flow rate exceeds a threshold amount.

5. The combined heat and power system of claim 1, wherein the alternator air outlet and the exhaust-to-coolant heat exchanger are located in the first chamber.

6. The combined heat and power system of claim 5, wherein the coolant-to-water heat exchanger, the coolant pump, the water pump, and alternator air inlet are located in the second chamber.

7. The combined heat and power system of claim 1, further comprising:

a controller configured to control operation of the coolant pump and the water pump;

wherein the housing further includes a third chamber and the controller is located in the third chamber.

8. The combined heat and power system of claim 7, further comprising:

a venting system configured to permit outside air to pass through the third chamber.

9. The combined heat and power system of claim 1, further comprising:

a chamber wall that divides the first chamber from the second chamber, wherein the passageway is formed through the chamber wall to allow air to pass between the first chamber and the second chamber.

10. The combined heat and power system of claim 9, wherein the air-to-water heat exchanger is attached to the chamber wall.

11. The combined heat and power system of claim 1, wherein the exhaust-to-coolant heat exchanger is further configured to operate as a muffler.

12. The combined heat and power system of claim 11, wherein the exhaust-to-coolant heat exchanger further comprises an expansion volume at least three times the size of the ETC exchanger exhaust inlet.

13. The combined heat and power system of claim 12, wherein exhaust is configured to enter the exhaust-to-coolant heat exchanger via the ETC exchanger exhaust inlet in a first direction, travel a second direction different than the first direction within the exhaust-to-coolant heat exchanger, and exit the exhaust-to-coolant heat exchanger via the ETC exchanger exhaust outlet in a third direction substantially the same as the first direction.

14. A combined heat and power system comprising:

a housing including a first chamber, a second chamber, and a passageway fluidly coupling the first chamber to the second chamber;

a coolant circuit including a coolant pump configured to pump coolant through the coolant circuit;

a liquid-cooled internal combustion engine including a liquid cooling system configured to cool the engine with coolant from the coolant circuit thereby heating the coolant;

an air-cooled alternator configured to be driven by the internal combustion engine to produce electricity, the alternator including an air cooling system configured to cool the alternator thereby heating air;

a water circuit including a housing water inlet, a housing water outlet, and a water pump configured to pump water through the water circuit, wherein the housing water inlet is configured to receive water from outside the housing and the housing water outlet is configured to output water from the housing;

an air-to-water heat exchanger configured to place heated air from the first chamber and water from the water circuit in a heat exchange relationship to preheat the water and cool the air;

a coolant-to-water heat exchanger configured to place heated coolant from the liquid cooling system and preheated water from the air-to-water heat exchanger in a heat exchange relationship to further heat the water and cool the coolant, wherein the coolant-to-water heat exchanger is fluidly coupled to the housing water outlet to provide heated water to the housing water outlet.

15. The combined heat and power system of claim 14, further comprising:

an exhaust-to-coolant heat exchanger configured to place exhaust from the engine and coolant from the coolant-to-water heat exchanger in a heat exchange relationship to heat the coolant and cool the exhaust.

16. The combined heat and power system of claim 14, further comprising:

a temperature sensor configured to sense a temperature of the heated water from the coolant-to-water heat exchanger;

a valve including a valve input fluidly coupled to the coolant-to-water heat exchanger to receive heated water, a recirculation outlet fluidly coupled to the air-to-water heat exchanger to recirculate heated water to the air-to-water heat exchanger, a hot water outlet fluidly coupled to the housing water outlet to provide heated water to the housing water outlet, wherein the valve is operable to output water from either the recirculation outlet or the hot water outlet; and

a controller configured to operate the valve to output water from the hot water outlet when the temperature sensed by water temperature sensor is greater than a target temperature and configured to output water from recirculation outlet when the temperature sensed by the water temperature sensor is less than the target temperature.

17. The combined heat and power system of claim 14, further comprising:

a variable frequency drive configured to drive the water pump at varying pump speeds.

18. The combined heat and power system of claim 17, further comprising:

a water flow sensor configured to sense a water flow rate in the water circuit;

a controller configured to provide a maintenance indicator when the pump speed when the water flow rate sensed by the water flow sensor is below a threshold flow rate exceeds a threshold amount.

19. The combined heat and power system of claim 14, further comprising:

a controller configured to control operation of the coolant pump and the water pump;

wherein the housing further includes a third chamber and the controller is located in the third chamber.

20. The combined heat and power system of claim 19, further comprising:

a venting system configured to permit outside air to pass through the third chamber.