Cogeneration system and method for controlling the same

• US 7,600,695 B2
• Filed: 01/24/2005
• Issued: 10/13/2009
• Est. Priority Date: 08/17/2004
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Choi, Chang Min, Choi, Won Jae, Lim, Hyung Soo, Kang, Seung Tak, Hwang, Yoon Jei
• Primary Examiner(s): BOLES, DEREK
• Application Number:
  US11/039,809
• Publication Number:
  US 20060037349A1
• Time in Patent Office: 1,723 Days
• Field of Search: 237/12.1, 237/2.R, 60/390.1, 607/93, 606/24
• US Class Current: 237/12.1
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2313/0233 in parallel arrangements
• CPC Class Codes: F25B 2327/001 of the internal combustion type
• CPC Class Codes: F25B 2400/06 Several compression cycles arranged in parallel
• CPC Class Codes: F25B 2500/02 Increasing the heating capacity of a reversible cycle during cold outdoor conditions
• CPC Class Codes: F25B 27/00 Machines, plants or systems, using particular sources of energy F25B30/06 takes precedence
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• CPC Class Codes: F25B 40/04 Desuperheaters
• CPC Class Codes: F25B 47/006 for preventing frost
• CPC Class Codes: Y02A 30/274 using waste energy, e.g. from internal combustion engine
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]

Abstract

A cogeneration system and a method for controlling the cogeneration system in which waste heat of an engine is mainly used to prevent an outdoor heat exchanger from being frosted, or is used not only to prevent the outdoor heat exchanger from being frosted, but also to enhance the heating performance of an indoor heat exchanger, in accordance with ambient temperature conditions, so that the cogeneration system can positively cope with ambient temperature conditions, and can exhibit a high energy efficiency.

Claims

1. A cogeneration system comprising:

an engine;

a generator connected to an output shaft of the engine to generate electricity;

a heat pump type air conditioner including a compressor, a directional valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger;

a pre-heater to pre-heat outdoor air blown toward the outdoor heat exchanger;

a compressor discharge line heater to heat a refrigerant discharged from the compressor; and

a waste heat controller to transfer waste heat from the engine to at least one of the pre-heater and the compressor discharge line heater while controlling the amount of the waste heat transferred to the preheater and the compressor discharge line heater,

wherein the waste heat controller comprises;

a cooling water heat exchanger to absorb heat from cooling water used to cool the engine;

an exhaust gas heat exchanger to absorb heat from exhaust gas discharged from the engine;

a first heat medium circulation conduit to guide a first heat medium to be circulated through the cooling water heat exchanger and the pre-heater;

a first circulation pump to pump the first heat medium for circulation of the first heat medium;

a second heat medium circulation conduit to guide a second heat medium to be circulated through the exhaust gas heat exchanger and the compressor discharge line heater;

a second circulation pump to pump the second heat medium for circulation of the second heat medium;

a heat medium heater arranged at the first heat medium circulation conduit to heat the first heat medium emerging from the cooling water heat exchanger; and

an exhaust gas path switching means for selectively supply the exhaust gas discharged from the engine to the heat medium heater or to the exhaust gas heat exchanger; and

wherein the exhaust gas path switching means comprises;

an exhaust conduit to guide the exhaust gas discharged from the engine to the exhaust gas heat exchanger;

a branched conduit to guide the exhaust gas discharged from the engine to the heat medium heater; and

a control valve to alternately open/close the exhaust conduit and the branched conduit.

2. The cogeneration system according to claim 1, wherein the exhaust gas path switching means further comprises:

a temperature sensor to measure a temperature of outdoor air or a temperature of the outdoor heat exchanger; and

a controller to control the control valve based on whether the heat pump type air conditioner operates in a heating mode or in a cooling mode, and the temperature measured by the temperature sensor.

3. The cogeneration system according to claim 2, wherein:

the controller controls the control valve to operate in a heat medium heater mode to close the exhaust conduit and to open the branched conduit when the heat pump type air conditioner operates in the heating mode, and the temperature measured by the temperature sensor is in a first predetermined temperature range; and

the controller controls the control valve to operate in an exhaust gas heat exchanger mode to open the exhaust conduit and to close the branched conduit when the heat pump type air conditioner operates in the heating mode, and the temperature measured by the temperature sensor is in a second predetermined temperature range, or when the heat pump type air conditioner operates in the cooling mode.

4. The cogeneration system according to claim 1, wherein at least one of the engine, the generator, the compressor, the directional valve, the outdoor heat exchanger, the expansion device, and the indoor heat exchanger comprises a plurality of ones.

5. The cogeneration system according to claim 1, wherein the heat pump type air conditioner uses the electricity generated from the generator.

6. A cogeneration system comprising:

an engine;

a generator connected to an output shaft of the engine to generate electricity;

a heat pump type air conditioner including a compressor, a directional valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger;

a pre-heater to pre-heat outdoor air blown toward the outdoor heat exchanger;

a compressor discharge line heater to heat a refrigerant discharged from the compressor; and

a waste heat controller to concentratedly transfer waste heat of the engine to the pre-heater when the outdoor heat exchanger is under a frost condition, and to transfer the waste heat of the engine to the pre-heater and the compressor discharge line heater in a distributed manner when the outdoor heat exchanger is not under the frost condition,

wherein the waste heat controller comprises;

a cooling water heat exchanger to absorb heat from cooling water used to cool the engine;

an exhaust gas heat exchanger to absorb heat from exhaust gas discharged from the engine;

a first heat medium circulation conduit to guide a first heat medium to be circulated through the cooling water heat exchanger and the pre-heater;

a first circulation pump to pump the first heat medium for circulation of the first heat medium;

a second heat medium circulation conduit to guide a second heat medium to be circulated through the exhaust gas heat exchanger and the compressor discharge line heater;

a second circulation pump to pump the second heat medium for circulation of the second heat medium;

a heat medium heater arranged at the first heat medium circulation conduit to heat the first heat medium emerging from the cooling water heat exchanger; and

exhaust gas path switching means for selectively supply the exhaust gas discharged from the engine to the heat medium heater or to the exhaust gas heat exchanger.

7. The cogeneration system according to claim 6, wherein the exhaust gas path switching means comprises:

an exhaust conduit to guide the exhaust gas discharged from the engine to the exhaust gas heat exchanger;

a branched conduit to guide the exhaust gas discharged from the engine to the heat medium heater; and

a control valve to alternately open/close the exhaust conduit and the branched conduit.

8. The cogeneration system according to claim 7, wherein the exhaust gas path switching means further comprises:

a temperature sensor to measure a temperature of outdoor air or a temperature of the outdoor heat exchanger; and

a controller to control the control valve based on whether the heat pump type air conditioner operates in a heating mode or in a cooling mode, and the temperature measured by the temperature sensor.

9. The cogeneration system according to claim 8, wherein:

the controller controls the control valve to operate in a heat medium heater mode to close the exhaust conduit and to open the branched conduit when the heat pump type air conditioner operates in the heating mode, and the temperature measured by the temperature sensor is in a first predetermined temperature range; and

the controller controls the control valve to operate in an exhaust gas heat exchanger mode to open the exhaust conduit and to close the branched conduit when the heat pump type air conditioner operates in the heating mode, and the temperature measured by the temperature sensor is in a second predetermined temperature range, or when the heat pump type air conditioner operates in the cooling mode.

10. The cogeneration system according to claim 6, wherein at least one of the engine, the generator, the compressor, the directional valve, the outdoor heat exchanger, the expansion device, and the indoor heat exchanger comprises a plurality of ones.

11. The cogeneration system according to claim 6, wherein the heat pump type air conditioner uses the electricity generated from the generator.