CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2019-0168126, filed Dec. 16, 2019, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a gas heat-pump system and, more particularly, to a gas heat-pump system capable of supplying recirculation exhaust gas to an engine using an exhaust gas turbocharger and thus actively controlling an amount of the flowing recirculation exhaust gas and pressure thereof.

Description of the Related Art

A heat-pump system is a system that is capable of performing a cooling or heating operation through refrigeration cycle, and operates in cooperation with a hot water supply apparatus or a cooling and heating apparatus.

That is, hot water is produced or air conditioning for cooling and heating is performed using a heat source that is obtained as a result of heat exchange occurring between cooling refrigerant in the refrigeration cycle and a predetermined heat storage medium.

Generally, a configuration for the refrigeration cycle requires that a compressor compressing refrigerant, a condenser condensing the refrigerant compressed by the compressor, an expansion device decompressing the refrigerant condensed by the condenser, and an evaporator evaporating the decompressed refrigerant are included.

The heat-pump systems are categorized into electric heat-pump systems and gas heat-pump systems according to a type of drive source for driving the compressor.

The electric heat-pump systems, which have a low load capacity, are suitable for family use.

The gas heat-pump systems, which have a high load capacity, are suitable for industrial use or for large buildings.

Therefore, instead of an electric motor, the gas heat-pump system uses a gas engine in order to drive a high capacity compressor suitable for this high load capacity.

The gas heat-pump system is configured to include an engine that burns a mixture of gaseous and air and (hereinafter referred to as a “fuel-to-air mixture”) and thus generates a motive force, a fuel supply device, a mixer for mixing air and gaseous fuel, and a device for supplying the fuel-to-air mixture to the engine.

Since the gas heat pump system uses a motive force of the engine, which is generated by combusting the fuel-to-air mixture, harmful substances contaminating the atmosphere are contained in exhaust gas generated in a process of combusting the fuel-to-air mixture.

Exhaust gas recirculation (EGR) technology in which a portion of the exhaust gas is resupplied to an intake line of the engine is generally employed as a means of reducing an amount of generated harmful substance contained in the exhaust gas.

Korean Patent Application Publication No. 10-2018-0015900 (Patent Document 1) discloses a turbocharger that rotates an impeller using a turbine, as a drive source, which is rotated with the exhaust gas, and an exhaust gas recirculation device that recirculates a portion of the exhaust discharged through the turbine to the intake line.

With a configuration disclosed in Patent Document 1, an amount of flowing recirculation exhaust gas is simply controlled only with an exhaust gas recirculation valve.

Therefore, in a case where pressure of the exhaust gas that is discharged and recirculated is lower than pressure of the intake line, recirculation is impossible.

In addition, with the configuration disclosed in Patent Document 1, an amount of the recirculation exhaust gas to be supplied cannot be controlled in a manner that corresponds to a concentration of harmful substances contained in the discharged exhaust gas or an amount of discharged substance. For this reason, the engine cannot be efficiently operated.

The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art.

SUMMARY OF THE INVENTION

An objective of the present disclosure is to provide a gas heat-pump system capable of supplying recirculation exhaust gas using an exhaust gas turbocharger and thus actively controlling an amount of flowing recirculation exhaust gas and pressure thereof.

Another objective of the present disclosure is to provide a gas heat-pump system capable of monitoring in real time a concentration of harmful substances contained in discharged exhaust gas and controlling an amount of recirculation exhaust gas on the basis of a result of the monitoring. In the gas heat-pump system, an amount of generated harmful substance can be remarkably reduced and the operational efficiency of an engine can be improved.

According to an aspect of the present disclosure, there is provided a gas heat-pump system, including: a compressor of a conditioning module; a gas engine combusting a fuel-to-air mixture and thus generating a drive force of the compressor; an exhaust gas turbocharger supplying at least a portion of exhaust gas discharged from the gas engine, as recirculation exhaust gas, to the gas engine; and a controller controlling an amount of the recirculation exhaust to be supplied, wherein the exhaust gas turbocharger includes: a turbine rotated with the exhaust gas; and an exhaust gas impeller rotated along with the turbine, the exhaust gas impeller being configured to apply pressure to the recirculation exhaust gas and supply the resulting recirculation exhaust gas to the gas engine, and the controller controls an amount of the flowing exhaust gas to be supplied to the turbine according to a concentration of harmful substances contained in the exhaust gas.

The gas heat-pump system may further include: an exhaust pipe through which the exhaust gas is discharged to the outside of the gas heat-pump system; a first bypass pipe provided to branch off from the exhaust pipe, the first bypass pipe being configured to guide at least a portion of the exhaust gas to the turbine; a second bypass pipe provided to branch off from the exhaust pipe downstream from the first bypass pipe, the second bypass pipe being configured to guide at least a portion of the exhaust gas, as the recirculation exhaust gas, the exhaust gas impeller; and an exhaust bypass valve installed on the bypass pipe, the exhaust bypass valve being configured to control an amount of the flowing exhaust gas to be introduced into the first bypass pipe, wherein the controller may control the degree of opening to which the exhaust bypass is open and thus may control the amount of the flowing exhaust gas to be introduced into the first bypass pipe.

In the gas heat-pump system, the exhaust bypass valve may be arranged between an entrance portion of the first bypass pipe through which the exhaust gas is introduced, and an exit portion of the first bypass valve through which the introduced exhaust gas is discharged.

The gas heat-pump system may further include: an exhaust gas sensor arranged downstream from an entrance portion of the second bypass pipe, the exhaust gas sensor being configured to sense the concentration of the harmful substances contained in the exhaust gas, wherein the controller may receive a signal indicative of the concentration of the harmful substances from the exhaust gas sensor and may calculate the concentration of the harmful substances.

In the gas heat-pump system, the harmful substances may include at least one of carbon monoxide, nitrogen oxide, and hydrocarbon.

In the gas heat-pump system, the controller may compare the calculated concentration with a reference concentration and may determine whether or not the calculated concentration exceeds the reference concentration, and when it is determined that the calculated concentration is equal to or higher than the reference concentration, the controller may decrease the degree of opening to which the exhaust bypass valve is open and thus may increase the amount of the flowing exhaust gas to be introduced into the first bypass pipe.

In the gas heat-pump system, the controller may compute a current rpm of the gas engine and an amount of required load on the air conditioning module, may compute a total amount of the flowing exhaust gas discharged from the gas engine on the basis of at least one of the computed current rpm and the computed amount of the required load, and may set the degree of opening to which the exhaust bypass valve is open, on the basis of the total amount of the flowing exhaust gas.

The gas heat-pump system may further include: a turbocharger applying pressure to the fuel-to-air mixture and supplying the resulting fuel-to-air mixture to the gas engine, wherein the controller may compute a current rpm of the gas engine, an amount of required load on the air conditioning module, and an rpm of the turbocharger, may compute a total amount of the flowing exhaust gas discharged from the gas engine on the basis of one of the computed current rpm, the computed amount of the required load, and the computed rpm of the turbocharger, and may set the degree of opening to which the exhaust bypass valve is open, on the basis of the total amount of the flowing exhaust gas.

The gas heat-pump system may further include: an intake manifold supplying the fuel-to-air mixture to the gas engine; an intake manifold pressure sensor sensing pressure of the fuel-to-air mixture within the intake manifold; and a recirculation exhaust gas pressure sensor sensing turbocharger pressure of the recirculation exhaust gas discharged from the exhaust gas turbocharger, wherein the controller may receive a signal indicative of the pressure of the fuel-to-air mixture from the intake manifold pressure sensor and may calculate the pressure of the fuel-to-air mixture, and the controller may receive a signal indicative of pressure of the recirculation exhaust gas from the recirculation exhaust gas pressure sensor and may calculate the turbocharger pressure of the recirculation exhaust gas to be supplied to the intake manifold.

In the gas heat-pump system, the controller may compute a pressure difference between the calculated pressure of the fuel-to-air mixture and the calculated turbocharger pressure of the recirculation exhaust gas, and may determine whether or not the pressure difference exceeds a predetermined reference pressure difference.

In the gas heat-pump system, when it is determined that the pressure difference is equal to or higher than the predetermined reference pressure difference, the controller may maintain the degree of opening to which the exhaust bypass valve is open.

In the gas heat-pump system, when it is determined that the pressure difference is lower than the predetermined reference pressure difference, the controller may decrease the degree of opening to which the exhaust bypass valve is open, at a predetermined ratio.

The gas heat-pump system may further include: an exhaust gas heat exchanger installed on the exhaust pipe in a manner that is arranged between an exit portion of the first bypass pipe and an entrance portion of the second bypass pipe.

The gas heat-pump system may further include: a check valve installed on an exit portion of the second bypass pipe, the check valve being configured to block the fuel-to-air mixture from flowing in a reverse direction from the gas engine to the second bypass pipe.

The gas heat-pump system according to the present disclosure supplies the recirculation exhaust gas using the exhaust gas turbocharger. Thus, the advantage of actively controlling the amount of the flowing recirculation exhaust gas and the pressure thereof can be achieved.

Furthermore, in the gas heat-pump system according to the present disclosure, the concentration of the harmful substances contained in the discharged exhaust gas is monitored in real time, and the amount of the recirculation exhaust gas is controlled on the basis of a result of the monitoring. Thus, the advantage of remarkably reducing the amount of the generated harmful substance and improving the operational efficiency of the gas engine can be archived.

