Control method of heat pump device capable of being driven by multiple energy sources

Abstract

The invention discloses a control method of a heat pump device capable of being driven by multiple energy sources, relates to the technical field of heat pumps, and solves the technical defects that an existing heat pump is low in resource utilization rate, and natural gas and electric energy sources are not reasonably used. The air source heat pump system is defaulted to be powered by an external power supply to operate for refrigeration, and the combined heat and power generation system does not operate; when the gas electricity price ratio is lower than a preset value M, the cogeneration system is started by default to operate; during heating operation, when the gas electricity price ratio is equal to or larger than a preset value N, stop valves on a first set of circulating branch pipes and a second set of circulating branch pipes are closed, a first main pipe stop valve and a second main pipe stop valve are opened, the air source heat pump system defaults to be powered by an external power source to operate for heating, and the combined heat and power generation system does not operate; wherein the N value is greater than the M value. Appropriate natural gas or electric power energy is flexibly selected for driving, and energy is intelligently switched for use.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular to an improved device and control method for efficiently utilizing primary energy of a biomass gas heat pump. Background Art

[0002] Heat pump technology has been widely used in various fields of social production and life. Heat pump products such as heat pump air conditioners, heat pump water heaters, heat pump dryers, car heat pumps, etc. meet people's different usage needs. The operating principle of a heat pump air conditioner is based on the reverse Carnot cycle in thermodynamics. Its working process can be described as a closed loop consisting of four main stages: evaporation, compression, condensation, and expansion. The heating process begins in the evaporator, where the low-temperature liquid refrigerant absorbs heat from the surrounding environment and evaporates into a gas. During this process, heat from the external heat source is extracted and transferred to the refrigerant. The gaseous refrigerant enters the compressor, where its pressure and temperature are significantly increased. Mechanical energy is used to compress the refrigerant, raising its temperature and turning it into a high-temperature, high-pressure gas. This high-temperature, high-pressure gas is then transported to the condenser, where it releases heat, which can be used for indoor heating or hot water supply. As the refrigerant cools, it condenses and transforms into a liquid. It then enters the expansion valve, which controls the refrigerant flow and rapidly reduces its pressure. This decrease in pressure also lowers the temperature of the liquid refrigerant, preparing it for the next round of heat extraction in the evaporator. The cooling process is the opposite, absorbing heat from the room and dissipating it outdoors.

[0003] The vast majority of heat pumps currently on the market are powered by electricity, using electric compressors as their core power components. However, due to the limitations of power distribution infrastructure, the large-scale deployment of electric heat pumps could lead to problems such as transformer overload and voltage instability, necessitating additional investment in grid upgrades, such as increasing transformer capacity and modifying power lines. Furthermore, the use of heat pumps, particularly heat pump air conditioners, exhibits a pronounced cyclical nature, with high usage in summer and winter and low usage in spring and autumn. This leads to electricity shortages in summer and winter, and even power outages in some areas. Increasing power infrastructure development not only requires significant investment and a long construction period, but also leaves excess power capacity unused during the spring and autumn seasons when electricity demand is low. Therefore, relying solely on grid power is currently insufficient to effectively promote the use of heat pumps. Existing power infrastructure and distribution capacity are far from sufficient to meet the growing demand of the heat pump market.

[0004] In addition to using grid electricity to power existing heat pumps, systems that utilize natural gas as a driving energy source, such as an engine driving the heat pump compressor, can also utilize natural gas as a driving energy source to achieve a cooling / heating cycle. However, the mechanical efficiency of the engine-driven compressor is only approximately 35%, and the remaining 65% of energy is stored as heat. Current heat pumps do not effectively utilize this heat, resulting in a waste of resources. Furthermore, natural gas prices may vary by region, and grid electricity is typically charged based on supply and demand and time of day. Therefore, the scientific and rational utilization of natural gas and electricity to power heat pumps remains a challenging technical challenge. Summary of the Invention

[0005] In summary, the purpose of the present invention is to solve the technical deficiencies of existing heat pumps, such as low resource utilization and unreasonable use of natural gas and electric energy, and to propose a control method for a heat pump device that can be driven by multiple energy sources.

[0006] In order to solve the technical deficiencies proposed by the present invention, the technical solutions adopted are: A control method for a heat pump device capable of being driven by multiple energy sources, characterized in that: the heat pump device capable of being driven by multiple energy sources comprises an air source heat pump system, a cogeneration system, a user-side heat exchanger, and a control system for controlling whether the air source heat pump system is powered by an external power supply or the cogeneration system; the air source heat pump system comprises a compressor, an oil separator, a four-way valve, a condenser, an electronic expansion valve, a liquid reservoir, an evaporator, a fan, and a gas-liquid separator; the compressor is respectively connected to the oil separator and the gas-liquid separator, the four-way valve is respectively connected to the oil separator, the gas-liquid separator, the evaporator, and the condenser, the condenser, the liquid reservoir, the electronic expansion valve, and the evaporator are connected in sequence, and the fan is arranged on the evaporator; The cogeneration system includes a generator set, a radiator, a jacket water heat exchanger and a flue gas waste heat recovery device; the generator set provides the power required for the operation of the air source heat pump system, the jacket heat dissipation circulation pipe of the generator set is connected to the radiator and the jacket water heat exchanger at the same time, and the flue gas waste heat recovery device is arranged on the exhaust pipe of the generator set; the flue gas waste heat recovery device and the jacket water heat exchanger are respectively connected to the main circulation pipe through the first group of circulation branches and the second group of circulation branches, and the first group of circulation branches and the second group of circulation branches are respectively provided with a stop valve, and the main circulation pipe is connected in series with a water pump, a user-side heat exchanger, a first main pipe stop valve, a second main pipe stop valve and a condenser; the first main pipe stop valve is arranged on the main circulation pipe between the water inlet and the water outlet of the first group of circulation branches; the second main pipe stop valve is arranged on the main circulation pipe between the water inlet and the water outlet of the second group of circulation branches; The control system uses the following method to control the air source heat pump system and the cogeneration system: During cooling operation: the stop valves on the first and second groups of circulation branches are closed, and the first main stop valve and the second main stop valve are opened. When the gas-to-electricity price ratio is equal to or greater than the preset value M, the air source heat pump system defaults to being powered by an external power supply for cooling, and the cogeneration system does not operate; when the gas-to-electricity price ratio is lower than the preset value M, the cogeneration system is started by default, and the air source heat pump system is driven by the power generated by the cogeneration system; During heating operation: when the gas When the electricity price ratio is equal to or greater than the preset value N, the stop valves on the first and second circulation branches are closed, the first and second main pipe stop valves are opened, and the air source heat pump system is powered by an external power supply for heating by default, while the cogeneration system does not operate; when the gas-to-electricity price ratio is lower than the preset value N, the stop valves on the first and second circulation branches are opened, the first and second main pipe stop valves are closed, and the cogeneration system is started by default, and the air source heat pump system is driven by the power generated by the cogeneration system; the N value is greater than the M value.

[0007] The technical features that further define the present invention include: The preset value M is 3.46; the preset value N is 4.77.

[0008] The condenser is connected to the main circulation pipe through a third group of circulation branches, and a stop valve is provided on the third group of circulation branches. A third main stop valve is provided on the main circulation pipe between the water inlet and the water outlet of the third group of circulation branches; when the air source heat pump system is in operation, the third main stop valve is closed and the stop valve on the third group of circulation branches is opened.

[0009] The beneficial effects of this invention are as follows: By combining cogeneration technology with electric heat pump technology, the invention flexibly selects the appropriate natural gas or electric power source, using electricity when appropriate and gas when appropriate, and can intelligently switch energy sources based on the price difference between gas and electricity. At the same time, the load of a single system can be adjusted to meet the needs of different scenarios. In addition, existing electric heat pumps can also be modified, greatly improving the promotion and practicality of the technology.

[0010] Illustrations Figure 1 This is a schematic structural diagram of a heat pump device capable of being driven by multiple energy sources according to the present invention. DETAILED DESCRIPTION

[0011] The present invention will be further described below with reference to the accompanying drawings and preferred specific embodiments of the present invention.

[0012] Reference Figure 1 As shown in the figure, the present invention discloses a control method for a heat pump device that can be driven by multiple energy sources, which is aimed at a heat pump device that can be driven by multiple energy sources, including an air source heat pump system 2, a cogeneration system 1, a user-side heat exchanger 3, and a control system for controlling the air source heat pump system 2 to use an external power supply or the cogeneration system 1 for power supply.

[0013] The specific structure of the air source heat pump system 2 includes a compressor, an oil separator, a four-way valve, a condenser, an electronic expansion valve, a liquid reservoir, an evaporator, a fan and a gas-liquid separator; the compressor is connected to the oil separator and the gas-liquid separator respectively, the four-way valve is connected to the oil separator, the gas-liquid separator, the evaporator and the condenser respectively, the condenser, the liquid reservoir, the electronic expansion valve and the evaporator are connected in sequence, and the fan is arranged on the evaporator; the air source heat pump system 2 is based on the reverse Carnot cycle principle in thermodynamics, thereby achieving cooling or heating.

[0014] The cogeneration system 1 includes a generator set, a radiator, a cylinder water heat exchanger and a flue gas waste heat recovery device; the generator set includes an engine powered by natural gas and a generator driven by the engine; the air source heat pump system 2 can be powered by an external power supply and operate independently, or the generator set can provide the power required for the operation of the air source heat pump system.

[0015] When the air source heat pump system 2 and the cogeneration system 1 are in the startup and operation state at the same time, in order to realize the recovery and utilization of the heat energy of the cogeneration system 1, the cylinder liner heat dissipation circulation pipe of the generator set is connected to the radiator and the cylinder liner water heat exchanger at the same time, and the flue gas waste heat recovery device is arranged on the exhaust pipe of the generator set; the heat generated by the combustion of natural gas by the generator set on the cylinder liner and the exhaust pipe is absorbed through the cylinder liner water heat exchanger and the flue gas waste heat recovery device.

[0016] In order to transfer the heat absorbed by the jacket water heat exchanger and the flue gas waste heat recovery device, together with the heat on the condenser, to the user-side heat exchanger, thereby improving the energy efficiency during heating of the present invention, the flue gas waste heat recovery device and the jacket water heat exchanger are connected to the main circulation pipe through a first group of circulation branches and a second group of circulation branches, respectively. The first group of circulation branches and the second group of circulation branches are respectively provided with a stop valve. The main circulation pipe is connected in series with a water pump, a user-side heat exchanger, a first main pipe stop valve 11, a second main pipe stop valve 12 and a condenser; the first main pipe stop valve 11 is provided on the main circulation pipe between the water inlet and the water outlet of the first group of circulation branches; the second main pipe stop valve 12 is provided on the main circulation pipe between the water inlet and the water outlet of the second group of circulation branches.

[0017] In order to better recover the heat absorbed by the jacket water heat exchanger and the flue gas waste heat recovery device when the present invention uses the cogeneration system 1 alone to supply power to the outside, the condenser and the main circulation pipe can be connected through a third group of circulation branches, and a stop valve is provided on the third group of circulation branches. A third main stop valve 13 is provided on the main circulation pipe between the water inlet and the water outlet of the third group of circulation branches; when the air source heat pump system is in operation, the third main stop valve 13 is closed and the stop valve on the third group of circulation branches is opened.

[0018] The control system of the present invention uses the following method to control the air source heat pump system and the cogeneration system: During cooling operation: the stop valves on the first and second circulation branches are closed, the stop valve on the third circulation branch is opened, the first and second main pipe stop valves are opened, and the third main pipe stop valve is closed. When the gas-to-electricity price ratio is equal to or greater than the preset value M, the air source heat pump system defaults to operating with external power supply for cooling, and the cogeneration system does not operate; when the gas-to-electricity price ratio is lower than the preset value M, the cogeneration system is started by default, and the air source heat pump system is driven by the power generated by the cogeneration system; During heating operation: when the gas-electricity price ratio is equal to or greater than the preset value N, the stop valves on the first and second circulation branches are closed, the stop valve on the third circulation branch is opened, the first and second main pipe stop valves are opened, and the third main pipe stop valve is closed. The air source heat pump system defaults to operating with external power supply for heating, and the cogeneration system does not operate; when the gas-electricity price ratio is lower than the preset value N, the stop valves on the first and second circulation branches are opened, the stop valve on the third circulation branch is opened, the first and second main pipe stop valves are closed, and the third main pipe stop valve is closed. The cogeneration system is started by default, and the air source heat pump system is driven by the power generated by the cogeneration system; The N value is greater than the M value. Through comparative analysis of natural gas prices and electricity prices, the present invention has been verified through a large number of experiments, and the preferred solution is: the preset value M is 3.46; the preset value N is 4.77. In the two operating modes, the control system of the present invention automatically switches the heat pump energy supply mode according to the corresponding gas-electricity price ratio to achieve the purpose of maximum economic efficiency of the heat pump operation.

[0019] In the specific implementation process, the economic operation of a heat pump device that can be driven by multiple energy sources disclosed in the present invention is closely related to the system energy efficiency. Taking the rated operating conditions of a certain air source heat pump as an example, when the ambient temperature is 35°C for rated cooling, the air source heat pump energy efficiency is 3.2, and the cooling capacity is 150kW. When the ambient temperature is 7°C for rated heating, the air source heat pump energy efficiency is 3.4, and the heating capacity is 170kW. The calorific value of natural gas is 8500kcal / Nm³, the cogeneration power generation efficiency is 35%, and the waste heat recovery efficiency is 45%. The energy efficiency during cooling and heating operation is calculated respectively.

[0020] 1. At rated cooling: If using an external power supply for direct drive, the power consumption is 150kW / 3.2=46.88kW. If using natural gas for drive, the power demand is 46.88kW, and the gas consumption is 46.88kW / 0.35=133.94kW. The primary energy efficiency (PER) is 150kW / 133.94kW=1.12, and the natural gas consumption is 133.94kW*(860kcal / kW) / 8500kcal / Nm³=13.55Nm³.

[0021] 2. Rated heating: If using external power direct drive, the power consumption is 170kW / 3.4=50.00kW. If using natural gas drive, the power generation power requirement is 50.00kW, and the gas power consumption is 50.00kW / 0.35=142.86kW. At the same time, the waste heat recovery is 142.86kW*45%=64.28kW, so the total heating capacity is 170kW+64.28kW=234.28kW, the primary energy efficiency PER is 234.28kW / 142.86kW=1.64, and the natural gas consumption is 142.86kW*(860kcal / kW) / 8500kcal / Nm³=14.45Nm³. In order to reflect the fairness of the economic comparison, the heating capacity when driven by natural gas is also controlled at 170kW. The gas power consumption is 170kW / 1.64=103.65kW, and the natural gas consumption is 103.65kW*(860kcal / kW) / 8500kcal / Nm³=10.48Nm³.

[0022] Based on the above calculation data, if the electricity price is 1 yuan / kWh, the hourly cost of using an electric direct-drive air source heat pump for cooling is 46.88kW*1 yuan / kWh=46.88 yuan. If the operating cost of using natural gas is to be on par with electricity, the unit price of natural gas should be 46.88 yuan / 13.55Nm³=3.46 yuan / Nm³. In other words, when the gas-to-electricity price ratio is 3.46, the economic efficiency of using electricity for cooling operation of a multi-energy heat pump device is the same as that of using natural gas. When the gas-to-electricity price ratio is lower than 3.46, using natural gas is more economical, and when the gas-to-electricity price ratio is higher than 3.46, using electricity is more economical.

[0023] The same principle applies to heating operation as for cooling. The hourly cost of an electric-powered air-source heat pump is 50.00kW*1 yuan / kWh = 50.00 yuan. To maintain the same operating costs using natural gas, the unit price of natural gas should be 50.00 yuan / 10.48 Nm³ = 4.77 yuan / Nm³. This means that when the gas-to-electricity price ratio is 4.77, the electricity cost of a multi-energy heat pump is the same as that of natural gas. When the gas-to-electricity price ratio is below 4.77, natural gas is more economical. When the gas-to-electricity price ratio is above 4.77, electricity is more economical.

[0024] It should be noted that in the area where the multi-energy heat pump device of the present invention is used, if time-of-use electricity prices are available, they can be entered separately according to the time, and the time period can also be manually modified. The control system detects and calculates the gas-to-electricity price ratio in real time and adjusts the device drive mode accordingly. The above energy drive modes can all be manually selected to meet the needs of different scenarios, such as using natural gas during power outages, electricity during gas outages, and gas when the grid load is insufficient. Flexible selection improves energy safety.

[0025] The above solution only takes the air source heat pump as an example and is not limited to the air source heat pump. The solution is also applicable to water source heat pump, ground source heat pump and other heat pump types, which illustrates the expansion of the protection scope of this patent.

[0026] The technical solution of the present invention is as follows: 1. A combined heat and power (CHP) system combines gas with an electric heat pump. The CHP system burns gas to generate electricity, which drives the electric heat pump. Meanwhile, waste heat is recovered to produce hot water for heating output in conjunction with the heat pump, improving the heat pump's heating capacity and enabling the heat pump to operate at full capacity regardless of whether it is powered by electricity or gas. 2. The energy usage mode can be intelligently adjusted based on the set gas-electricity price difference, inferring based on operating energy efficiency. When gas is more economical, gas is used as the driving energy source, and when electricity is more economical, electricity is used. By recycling waste heat, this heat can be used to produce hot water for heating or domestic hot water, etc.

Claims

1. A control method for a heat pump device capable of being driven by multiple energy sources, characterized in that: The multi-energy driven heat pump device includes an air source heat pump system, a cogeneration system, a user-side heat exchanger, and a control system for controlling whether the air source heat pump system is powered by an external power supply or the cogeneration system; The air source heat pump system includes a compressor, an oil separator, a four-way valve, a condenser, an electronic expansion valve, a liquid reservoir, an evaporator, a fan and a gas-liquid separator; the compressor is connected to the oil separator and the gas-liquid separator respectively, the four-way valve is connected to the oil separator, the gas-liquid separator, the evaporator and the condenser respectively, the condenser, the liquid reservoir, the electronic expansion valve and the evaporator are connected in sequence, and the fan is arranged on the evaporator; The cogeneration system includes a generator set, a radiator, a jacket water heat exchanger, and a flue gas waste heat recovery device; the generator set provides the power required for the operation of the air source heat pump system, the generator set's jacket heat dissipation circulation pipe is connected to the radiator and the jacket water heat exchanger at the same time, and the flue gas waste heat recovery device is installed on the exhaust pipe of the generator set; The flue gas waste heat recovery device and the cylinder water heat exchanger are connected to the main circulation pipe through the first group of circulation branches and the second group of circulation branches respectively. The first group of circulation branches and the second group of circulation branches are respectively provided with a stop valve. The main circulation pipe is connected in series with a water pump, a user-side heat exchanger, a first main pipe stop valve, a second main pipe stop valve and a condenser; the first main pipe stop valve is arranged on the main circulation pipe between the water inlet and the water outlet of the first group of circulation branches; the second main pipe stop valve is arranged on the main circulation pipe between the water inlet and the water outlet of the second group of circulation branches; The control system controls the air source heat pump system and the cogeneration system using the following method: During cooling operation: the stop valves on the first and second circulation branches are closed, the first and second main pipe stop valves are opened, and when the gas-to-electricity price ratio is equal to or greater than the preset value M, the air source heat pump system defaults to operating with external power supply for cooling, and the cogeneration system does not operate; When the gas-to-electricity price ratio is lower than the preset value M, the cogeneration system is started by default, and the air source heat pump system is driven by the power generated by the cogeneration system; During heating operation: When the gas-to-electricity price ratio is equal to or greater than the preset value N, the stop valves on the first and second circulation branches are closed, and the first and second main pipe stop valves are opened. The air source heat pump system defaults to operating with external power supply for heating, while the cogeneration system does not operate. When the gas-to-electricity price ratio is lower than the preset value N, the stop valves on the first and second circulation branches are opened, and the first and second main pipe stop valves are closed. The cogeneration system is started by default, and the air source heat pump system is driven by the power generated by the cogeneration system. The N value is greater than the M value.

2. The control method of a heat pump device capable of being driven by multiple energy sources according to claim 1, characterized in that: The preset value M is 3.46; the preset value N is 4.

77.

3. The control method of a heat pump device capable of being driven by multiple energy sources according to claim 1, characterized in that: The condenser is connected to the main circulation pipe through a third group of circulation branches, and a stop valve is provided on the third group of circulation branches. A third main stop valve is provided on the main circulation pipe between the water inlet and the water outlet of the third group of circulation branches; when the air source heat pump system is in operation, the third main stop valve is closed and the stop valve on the third group of circulation branches is opened.

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