Heat medium circulation structure and hot water temperature control method for micro combined heat and power generator

Patent metadata

Field	Value
Publication number	US-10180116-B2
Application number	US-201515322057-A
Country	US
Kind code	B2
Filing date	Jun 10, 2015
Priority date	Jun 27, 2014
Publication date	Jan 15, 2019
Grant date	Jan 15, 2019

Abstract

The present invention provides a heat medium circulation structure for a micro-combined heat and power (micro-CHP) generator in which a heat medium that primarily looses heat by undergoing heat exchange with water in a hot-water tank and thus has a low temperature further performs heat exchange with low-temperature direct water supplied through a direct water line, thereby further loosing heat, in a return line heat exchanger, and then returns to a stirling engine through a heat medium return line, thereby effectively cooling a low temperature portion of the stirling engine. Thus, the heat medium circulation structure enables high electricity production efficiency. Further provided is a hot water temperature control method for a micro-CHP generator in which the consumption of hot water is detected by a flow sensor. First and second predetermined temperatures are defined to operate a stirling engine in the case of temperature droppings of hot water respectively due to natural radiation and consumption of hot water.

First claim

The invention claimed is:

1. A heat medium circulation structure for a micro-combined heat and power (micro-CHP) generator, the structure comprising:
a stirling engine that produces electricity using a temperature difference between a temperature of an engine head which is heated by an engine burner and a temperature of a heat medium which returns from a hot water tank through a heat medium return line, wherein the engine head temperature is higher than the heat medium temperature;
a sensible heat exchanger disposed at one side of the stirling engine;
the hot water tank that receives the heat medium which is heated to a temperature by the stirling engine and the sensible heat exchanger and is then supplied thereto through a heat medium supply line, and allows the heated heat medium to perform heat-exchange with water stored therein, wherein the temperature of the heated heat medium supplied to the hot water tank is higher than the temperature of the heat medium returned from the hot water tank;
a direct water line through which direct water is supplied to the hot water tank to replenish the water stored in the hot water tank so that the hot water tank maintains a predetermined water level; and
a return line heat exchanger installed at the direct water line and before the hot water tank so that the direct water can perform heat exchange with the heat medium in the heat medium return line before being supplied to the hot water tank.

2. The heat medium circulation structure according to claim 1 , further comprising: a latent heat exchanger disposed at the one side of the stirling engine, wherein the hot water tank receives the heated heat medium that is heated by passing the stirling engine, the sensible heat exchanger, and the latent heat exchanger, and allows the heated heat medium to undergo heat exchange with the water stored therein.

3. The heat medium circulation structure according to claim 1 , further comprising: a circulation pump disposed between the return line heat exchanger and the stirling engine to adjust a flow rate of the heat medium that circulates and performs heat exchange with the direct water, in the return line heat exchanger, thereby adjusting the temperature of the heat medium supplied from the stirling engine.

4. A hot water temperature control method for a micro-combined heat and power generator, the method comprising:
a step of determining whether hot water is consumed by sensing a flow rate of direct water introduced into a hot water tank through a direct water line, using a flow sensor installed at one side of the direct water line, during operation of the micro-combined heat and power generator;
a step (S 12 ) of determining whether a temperature of the hot water stored in the hot water tank is lower than a first predetermined temperature so as to operate a stirling engine in case the temperature of the hot water drops due to consumption of the hot water, when it is determined that the hot water is consumed in the determining step;
a step of determining whether the temperature of the hot water stored in the hot water tank is lower than a second predetermined temperature so as to operate the stirling engine in case the temperature of the hot water drops due to natural radiation, when it is determined that the hot water is not consumed in the determining step;
a step of operating the stirling engine when it is determined that the temperature of the hot water is lower than the first predetermined temperature or the second predetermined temperature;
a step of adjusting a temperature of the heat medium supplied from the stirling engine by adjusting a flow rate of the heat medium using a circulation pump;
a step of determining whether the temperature of the hot water is lower than a third predetermined temperature at which the stirling engine needs to stop operating; and
a step of stopping the stirling engine that is operated in the operating step when it is determined that the temperature of the hot water is equal to or higher than the third predetermined temperature.

Assignees

• Kyungdong Navien Co Ltd

Inventors

• Park Dae Woong
• Jang Duck Pyo

Classifications

• F24D2101/80

  Electric generators driven by external combustion engines, e.g. Stirling engines · CPC title

• F24D2103/13

  characterised by their heat exchangers · CPC title

• F24D18/00

  Small-scale combined heat and power [CHP] generation systems specially adapted for domestic heating, space heating or domestic hot-water supply · CPC title

• F24H1/186

  using fluid fuel · CPC title

• F02G2243/00

  Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes · CPC title