A waste heat recovery energy-saving system for combined cooling and heating

Abstract

The present invention discloses a waste heat recovery and energy-saving system for combined cooling and heating, comprising a first hot water tank, a second hot water tank, a first heat pump unit, a second heat pump unit, a conversion water tank, a shell-and-tube heat exchanger, and a spiral pre-cooling tank. The first hot water tank is connected to the first heat pump unit via an electric temperature-sensing valve and a circulating water pump. The first hot water tank is connected to the second heat pump unit via an electric temperature-sensing valve and a circulating water pump. The first heat pump unit is connected to the shell-and-tube heat exchanger via the circulating water pump, and the first outlet of the shell-and-tube heat exchanger is connected to the second inlet of the first heat pump unit. The second outlet of the second heat pump unit is connected to the first inlet of the conversion water tank via an electric temperature-sensing valve, and the first outlet of the conversion water tank is connected to the second inlet of the second heat pump unit in turn via the electric temperature-sensing valve and the circulating water pump. The present invention fully recovers the low-grade condensation heat of the heat pump unit, maximizing waste heat recovery, and can simultaneously supply cold water and hot water for process production.

Description

Technical Field

[0001] The present invention belongs to the technical field of combined cooling and heating, and more particularly relates to a waste heat recovery and energy-saving system for combined cooling and heating. Background Art

[0002] The common waste heat utilization technologies currently used in China mainly include heat exchange technology, heat-to-work conversion technology, and waste heat cooling and heating technology. (1) Heat exchange technology is suitable for waste heat recovery at various temperatures, but the secondary energy utilization is limited by the efficiency of the heat exchanger, so the overall efficiency of the energy supply system is not high; (2) Heat-to-work conversion technology is suitable for medium and high temperature waste heat recovery, and can also be converted into electricity to facilitate long-distance energy transportation, but the recovery efficiency of low-grade waste heat is low; (3) Heat pump technology in waste heat cooling and heating technology is suitable for utilizing low-grade waste heat at 30-60℃, and the heating efficiency of the heat pump unit is between 3 and 5. It is a feasible technology for efficiently utilizing waste heat slightly higher than the ambient temperature, but the temperature of the cold and hot water of the heat pump unit limits its wide application and process production.

[0003] In recent years, with the rapid economic development of my country, waste heat losses from energy utilization have become increasingly severe. On the one hand, process production requires simultaneous access to cold and hot water at specific temperatures. Heat pump units, constrained by the laws of thermodynamics, struggle to meet the varying temperatures required by production processes. Even if these temperatures are met, operating efficiency is low, resulting in poor energy savings. On the other hand, the cooling demand of production processes is generally 5°C below the typical chilled water temperature in refrigeration cycles, while the heating demand is generally 40°C above the typical condensing water temperature in heating cycles. Furthermore, wastewater temperatures vary widely across various industries, making heat pump units unable to adapt to varying production conditions. This results in low utilization rates for low-grade waste heat, necessitating temperature conversion for cooling and heating purposes, further reducing energy efficiency. In summary, existing heat pump systems struggle to meet the varying loads and temperatures of cold and hot water required by production processes. Furthermore, the low-grade waste heat in the condensing water of heat pump units cannot be fully recovered and utilized, resulting in low overall energy efficiency for hot and cold water supply systems. Summary of the Invention

[0004] In light of this, the present invention provides a waste heat recovery and energy-saving system for combined cooling and heating. This system utilizes two heat pump units. One heat pump provides cooling while the condenser water heats two hot water tanks. The other heat pump unit's chilled water cools a transfer tank. The chilled water exchanges heat with a heat exchanger to produce low-temperature cold water at varying temperatures. The condensed water is then heated by a secondary series heat pump to produce hot water. This system fully recovers the low-grade condensation heat from the heat pump units, maximizing waste heat recovery. Furthermore, it can simultaneously supply both cold and hot water for process production. The transfer tank adjusts the temperature of the combined cooling and heating system's hot and cold water to meet the fluctuating heating and cooling needs of various users.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A waste heat recovery and energy-saving system for combined cooling and heating, comprising: a hot water tank 1, a hot water tank 2, a heat pump unit 1, a heat pump unit 2, a conversion water tank, a shell and tube heat exchanger and a spiral pre-cooling pool; wherein, the first outlet of the hot water tank 1 is connected to the first inlet of the heat pump unit 1 in sequence through an electric temperature-sensitive valve and a circulating water pump, and the first outlet of the heat pump unit 1 is connected to the first inlet of the hot water tank 1 through an electric temperature-sensitive valve; the second outlet of the hot water tank 1 is connected to the first inlet of the heat pump unit 2 in sequence through an electric temperature-sensitive valve and a circulating water pump, and the first outlet of the heat pump unit 2 is connected to the second inlet of the hot water tank 1 through an electric temperature-sensitive valve; the first outlet of the hot water tank 2 is connected to the first inlet of the heat pump unit 1 in sequence through an electric temperature-sensitive valve and a circulating water pump The first inlet of the heat pump unit is connected, the first outlet of the heat pump unit one is connected to the first inlet of the hot water tank two through an electric temperature-sensitive valve; the second outlet of the hot water tank two is connected to the first inlet of the heat pump unit two through the electric temperature-sensitive valve and the circulating water pump in sequence, and the first outlet of the heat pump unit two is connected to the second inlet of the hot water tank two through the electric temperature-sensitive valve; the second outlet of the heat pump unit one is connected to the first inlet of the shell and tube heat exchanger through the circulating water pump, and the first outlet of the shell and tube heat exchanger is connected to the second inlet of the heat pump unit one; the second outlet of the heat pump unit two is connected to the first inlet of the conversion water tank through the electric temperature-sensitive valve, and the first outlet of the conversion water tank is connected to the second inlet of the heat pump unit two through the electric temperature-sensitive valve and the circulating water pump in sequence.

[0007] Furthermore, solenoid valves for controlling the internal pressure of the water tanks are installed on the tops of the hot water tanks 1 and 2.

[0008] Furthermore, it also includes a temperature sensor for measuring the water temperature inside the water tank and a controller for controlling the operation of the system. The controller controls the operation mode of the waste heat recovery and energy-saving system according to the temperature information measured by the temperature sensor.

[0009] Furthermore, the hot water generated by heat pump unit 1 enters hot water tank 1 through electric temperature-sensitive valve 2, and the hot water generated by heat pump unit 1 enters hot water tank 2 through electric temperature-sensitive valve 4, and the heated water in hot water tank 1 and hot water tank 2 enters heat pump unit 2.

[0010] Furthermore, when the water temperature in the hot water tank 1 is equal to or greater than a first preset value, the electric temperature-sensing valve 4 is opened, the electric temperature-sensing valve 2 is closed, and other devices always remain in the open state.

[0011] Furthermore, the hot water generated by the heat pump unit 2 enters the hot water tank 1 through the electric temperature-sensitive valve 8, and the hot water generated by the heat pump unit 2 enters the hot water tank 2 through the electric temperature-sensitive valve 10, thereby obtaining high-temperature hot water.

[0012] Furthermore, when the water temperature in hot water tank one is equal to or greater than a second preset value, the solenoid valve one connecting hot water tank one to industrial water is opened, the solenoid valve two connecting hot water tank two to industrial water is opened, and other devices always remain in the open state.

[0013] Furthermore, in the first state, when the system is running under normal working conditions, in the first stage, tap water is injected into hot water tank 1 and hot water tank 2, electric temperature-sensitive valve 1 is opened, electric temperature-sensitive valve 3 is closed, and tap water is sent to heat pump unit 1 by circulating water pump 1 through electric temperature-sensitive valve 1. Tap water is exchanged in heat pump unit 1 to produce hot water. On the one side: electric temperature-sensitive valve 2 and electric temperature-sensitive valve 12 are opened, and electric temperature-sensitive valve 4 is closed. The hot water of the first preset value obtained by heat exchange heats the water in water tank 1, and the excess heat enters the conversion water tank. On the cold water side, cold water at -4.5°C is sent to the shell and tube heat exchanger through circulating water pump 1, and cold water at 1°C is obtained through heat exchange to supply the spiral pre-cooling pool; in the second stage, electric temperature-sensitive valve 4 is opened and electric temperature-sensitive valve 2 is closed. Closed, other equipment maintains the state of the first stage, and the hot water generated by the heat pump unit 1 continues to heat the water tank 2; in the third stage, on the basis of the first stage, the electric temperature-sensitive valve 7 is opened, the electric temperature-sensitive valve 9 is closed, and the hot water in the hot water tank 1 that reaches the first preset value is sent to the heat pump unit 2 by the circulating water pump 2 through the electric temperature-sensitive valve 7, and is converted again by the temperature of the heat pump unit 2. At this time, the electric temperature-sensitive valve 8 is opened first, and the electric temperature-sensitive valve 10 is kept closed. When the water in the hot water tank 1 reaches the second preset value, the electric temperature-sensitive valve 8 is closed, the electric temperature-sensitive valve 10 is opened, the solenoid valve 1 is opened, and the solenoid valve 2 is closed. At the same time, the electric temperature-sensitive valves 13, 18, and 19 are opened, and the cold water enters the conversion water tank, the water reservoir, the heat pump unit 1, and the heat pump unit 2.

[0014] Furthermore, in the second state, when the system is running under the condition of increased demand, hot water tank one and hot water tank two are running at the same time. In the first stage, tap water is injected into hot water tank one and hot water tank two, electric temperature-sensing valve one is opened, electric temperature-sensing valve three is opened, and the water in hot water tank one and hot water tank two is sent to heat pump unit one by circulating water pump one through electric temperature-sensing valve one and electric temperature-sensing valve three. Tap water is exchanged in heat pump unit one to produce hot water. On the one hand, electric temperature-sensing valve two and electric temperature-sensing valve twelve are opened, and electric temperature-sensing valve four is closed. The hot water of the first preset value obtained by heat exchange first heats the water in hot water tank one, and on the cold water side, cold water of -4.5℃ is sent to the shell and tube heat exchanger through circulating water pump one, and cold water of 1℃ is obtained by heat exchange to supply the spiral pre-cooling pool; in the second stage, electric temperature-sensing valve four is opened, electric temperature-sensing valve two is closed, and other devices The state of the first stage is maintained, and the hot water generated by the heat pump unit 1 continues to heat the water tank 2; in the third stage, on the basis of the first stage, the electric temperature-sensitive valve 7 and the electric temperature-sensitive valve 9 are kept open, and the hot water in the hot water tank 1 and the hot water tank 2 that reaches the first preset value is sent to the heat pump unit 2 by the circulating water pump 2 through the electric temperature-sensitive valve 7, and is converted again by the temperature of the heat pump unit 2. At this time, the electric temperature-sensitive valve 8 is opened first, and the electric temperature-sensitive valve 10 is closed. When the water in the hot water tank 1 reaches the second preset value, the electric temperature-sensitive valve 8 is closed, and the electric temperature-sensitive valve 10 is kept open to continue heating the hot water tank 2. When the water in the hot water tank 2 reaches the second preset value, the solenoid valve 1 and the solenoid valve 2 are opened at the same time. At the same time, the electric temperature-sensitive valve 13, the electric temperature-sensitive valve 18 and the electric temperature-sensitive valve 19 are opened, and the cold water enters the conversion water tank, the water reservoir and the refrigeration unit.

[0015] Furthermore, in the third state, when the system is running under low energy consumption conditions at night, and only heat is needed without cooling, the heat stored in the conversion water tank will be released when the system is running under low energy consumption, only meeting the heating demand. At this time, electric temperature sensing valve 1, electric temperature sensing valve 2, electric temperature sensing valve 3, electric temperature sensing valve 4, electric temperature sensing valve 5, electric temperature sensing valve 6, electric temperature sensing valve 11, and electric temperature sensing valve 12 are opened. Except for the conversion water tank, hot water tank 1 and hot water tank 2, other equipment remains closed.

[0016] The beneficial effects of the present invention are:

[0017] This invention utilizes two heat pump units. One heat pump provides cooling while the condenser water heats two hot water tanks. The other heat pump unit's chilled water cools a transfer tank. The chilled water exchanges heat with a heat exchanger to produce low-temperature cold water at varying temperatures. The condensed water is then heated by a secondary series heat pump to produce hot water. This system fully recovers the low-grade condensation heat of the heat pump units, maximizing waste heat recovery. It also provides both cold and hot water for process production. The transfer tank adjusts the temperature of the combined hot and cold water system to meet the fluctuating heating and cooling needs of various users. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 This is a system principle diagram of the first and second working conditions of a waste heat recovery energy-saving system for combined cooling and heating of the present invention (the two working conditions are distinguished by controlling the opening of the valve);

[0021] Figure 3 This is a system principle diagram of the third working condition of a waste heat recovery and energy-saving system for combined cooling and heating supply of the present invention (the bold part is the third working condition).

[0022] Among them, in the figure:

[0023] 1-hot water tank 1; 2-hot water tank 2; 3-heat pump unit 1; 4-heat pump unit 2; 5-conversion water tank; 6-shell and tube heat exchanger; 7-spiral pre-cooling tank; 8-circulating water pump 1; 9-circulating water pump 2; 10-circulating water pump 3; 11-circulating water pump 4; 12-circulating water pump 5; 13-electric temperature-sensing valve 1; 14-electric temperature-sensing valve 2; 15-electric temperature-sensing valve 3; 16-electric temperature-sensing valve 4; 17-electric temperature-sensing valve 5; 18-electric temperature-sensing valve 6; 19-electric temperature-sensing valve 7; 20-electric temperature-sensing valve 1-Electric temperature-sensing valve 8; 21-Electric temperature-sensing valve 9; 22-Electric temperature-sensing valve 10; 23-Electric temperature-sensing valve 11; 24-Electric temperature-sensing valve 12; 25-Electric temperature-sensing valve 13; 26-Electric temperature-sensing valve 14; 27-Electric temperature-sensing valve 15; 28-Electric temperature-sensing valve 16; 29-Electric temperature-sensing valve 17; 30-Electric temperature-sensing valve 18; 31-Electric temperature-sensing valve 19; 32-Butterfly valve 1; 33-Butterfly valve 2; 34-Butterfly valve 3; 35-Sight tube; 36-Thermometer; 37-Solenoid valve 1; 38-Solenoid valve 2. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] refer to Figure 1The present invention provides a waste heat recovery and energy-saving system for combined cooling and heating, comprising: a hot water tank 1, a hot water tank 2, a heat pump unit 1, a heat pump unit 2, a conversion water tank, a shell and tube heat exchanger, and a spiral pre-cooling pool; wherein, the first outlet of the hot water tank 1 is connected to the first inlet of the heat pump unit 1 in sequence through an electric temperature-sensitive valve and a circulating water pump, and the first outlet of the heat pump unit 1 is connected to the first inlet of the hot water tank 1 through an electric temperature-sensitive valve; the second outlet of the hot water tank 1 is connected to the first inlet of the heat pump unit 2 in sequence through an electric temperature-sensitive valve and a circulating water pump, and the first outlet of the heat pump unit 2 is connected to the second inlet of the hot water tank 1 through an electric temperature-sensitive valve; the first outlet of the hot water tank 2 is connected to the first inlet of the heat pump unit 2 in sequence through an electric temperature-sensitive valve The first inlet of heat pump unit 1 is connected to the first outlet of heat pump unit 1, which is connected to the first inlet of hot water tank 2 via an electric temperature-sensitive valve. The second outlet of hot water tank 2 is connected to the first inlet of heat pump unit 2 via the electric temperature-sensitive valve and the circulating water pump, and the first outlet of heat pump unit 2 is connected to the second inlet of hot water tank 2 via the electric temperature-sensitive valve. The second outlet of heat pump unit 1 is connected to the first inlet of the shell-and-tube heat exchanger via the circulating water pump, and the first outlet of the shell-and-tube heat exchanger is connected to the second inlet of heat pump unit 1. The second outlet of heat pump unit 2 is connected to the first inlet of the conversion water tank via the electric temperature-sensitive valve, and the first outlet of the conversion water tank is connected to the second inlet of heat pump unit 2 via the electric temperature-sensitive valve and the circulating water pump. Heat pump units 1 and 2 are each connected to the second inlet of the conversion water tank via an electric temperature-sensitive valve, and the second outlets are connected to the water well via the electric temperature-sensitive valve. The second outlet of the shell-and-tube heat exchanger is connected to the first inlet of the spiral pre-cooling tank via a thermometer and the circulating water pump, and the first outlet of the spiral pre-cooling tank is connected to the second inlet of the shell-and-tube heat exchanger.

[0026] Heat pump unit 2 4 is connected to heat pump unit 1 3 via a hot water tank. Heat pump unit 2 4 is used to recover the condensation heat generated by heat pump unit 1 3. After the hot water generated by heat pump unit 1 3 heats hot water tank 1, the water in hot water tank 1 undergoes temperature conversion again through heat pump unit 2 4 and eventually returns to hot water tank 2. Heat pump unit 1 3 exchanges heat with the shell and tube heat exchanger 6, and the cold water obtained is supplied to the spiral pre-cooling tank 7. In addition to being stored in the conversion water tank, the excess cold water generated by heat pump unit 2 is discharged into the water reservoir and well. Heat pump unit 1 exchanges heat with the shell and tube heat exchanger, and the cold water obtained is supplied to the spiral pre-cooling tank; the hot water generated by heat pump unit 2 through temperature conversion is directly supplied to production use.

[0027] In this embodiment, the electric temperature-sensing valve 18 and the electric temperature-sensing valve 19 are connected to the cold water of the heat pump unit 1 and the heat pump unit 2.

[0028] The tops of the hot water tanks 1 and 2 are both equipped with solenoid valves for controlling the internal pressure of the water tanks. The solenoid valves 1 and 2 are used to connect to the hot water system.

[0029] The present invention also includes a temperature sensor for measuring the water temperature inside the water tank and a controller for controlling the operation of the system. The controller controls the operation mode of the waste heat recovery and energy-saving system according to the temperature information measured by the temperature sensor.

[0030] The hot water generated by heat pump unit 1 enters hot water tank 1 through electric temperature-sensitive valve 2 14, and the hot water generated by heat pump unit 1 enters hot water tank 2 through electric temperature-sensitive valve 4 16. The heated water in hot water tank 1 and hot water tank 2 enters heat pump unit 2.

[0031] When the water temperature in the hot water tank 1 is equal to or greater than a first preset value, the electric temperature sensing valve 4 16 opens, the electric temperature sensing valve 2 14 closes, and other devices remain open. The first preset value is 45°C.

[0032] The hot water generated by the heat pump unit 2 enters the hot water tank 1 through the electric temperature-sensitive valve 8 20, and the hot water generated by the heat pump unit 2 enters the hot water tank 2 through the electric temperature-sensitive valve 10 22 to obtain high-temperature hot water.

[0033] When the water temperature in hot water tank 1 is equal to or greater than a second preset value, solenoid valve 13 connecting hot water tank 1 to the industrial water supply opens, solenoid valve 2 14 connecting hot water tank 2 to the industrial water supply opens, and all other devices remain open. The second preset value is 60°C.

[0034] This system is designed with three operating modes. The first state is the operating mode of the system under normal working conditions, the second state is the operating mode of the system under the working conditions of increased production demand, and the third state is the operating mode of the system under the working conditions of low energy consumption at night, as shown below:

[0035] In the first state, when the system is running under normal working conditions, in the first stage, tap water is injected into hot water tank 1 and hot water tank 2, electric temperature-sensitive valve 1 is opened, electric temperature-sensitive valve 3 is closed, and tap water is sent to heat pump unit 1 by circulating water pump 1 through electric temperature-sensitive valve 1. Tap water is exchanged in heat pump unit 1 to produce hot water. On the one side: electric temperature-sensitive valve 2 and electric temperature-sensitive valve 12 are opened, electric temperature-sensitive valve 4 is closed, and the hot water of the first preset value obtained by heat exchange heats the water in water tank 1, and the excess heat enters the conversion water tank. On the cold water side, -4.5℃ cold water is sent to the shell and tube heat exchanger through circulating water pump 1, and the cold water obtained by heat exchange is 1℃ to supply the spiral pre-cooling pool; in the second stage, electric temperature-sensitive valve 4 is opened, and electric temperature-sensitive valve 2 is closed. Other equipment maintains the state of the first stage, and the hot water generated by the heat pump unit 1 continues to heat the water tank 2; in the third stage, based on the first stage, the electric temperature-sensitive valve 7 is opened and the electric temperature-sensitive valve 9 is closed. The hot water in the hot water tank 1 that reaches the first preset value is sent to the heat pump unit 2 by the circulating water pump 2 through the electric temperature-sensitive valve 7, and is converted again by the temperature of the heat pump unit 2. At this time, the electric temperature-sensitive valve 8 is opened first, and the electric temperature-sensitive valve 10 is kept closed. When the water in the hot water tank 1 reaches the second preset value, the electric temperature-sensitive valve 8 is closed, the electric temperature-sensitive valve 10 is opened, the solenoid valve 1 is opened, and the solenoid valve 2 is closed. At the same time, the electric temperature-sensitive valves 13, 18, and 19 are opened, and the cold water enters the conversion water tank, the water reservoir, the heat pump unit 1, and the heat pump unit 2.

[0036] In the second state, when the system is running under the condition of increased demand, hot water tank 1 and hot water tank 2 are running at the same time. In the first stage, tap water is injected into hot water tank 1 and hot water tank 2, electric temperature-sensing valve 1 is opened, electric temperature-sensing valve 3 is opened, and the water in hot water tank 1 and hot water tank 2 is sent to heat pump unit 1 by circulating water pump 1 through electric temperature-sensing valve 1 and electric temperature-sensing valve 3. Tap water is exchanged in heat pump unit 1 to produce hot water. On the one side: electric temperature-sensing valve 2 and electric temperature-sensing valve 12 are opened, and electric temperature-sensing valve 4 is closed. The hot water of the first preset value obtained by heat exchange first heats the water in hot water tank 1. On the cold water side, cold water of -4.5℃ is sent to the shell and tube heat exchanger through circulating water pump 1, and cold water of 1℃ is obtained through heat exchange to supply the spiral pre-cooling pool. In the second stage, electric temperature-sensing valve 4 is opened, electric temperature-sensing valve 2 is closed, and other equipment is kept Maintaining the state of the first stage, the hot water generated by the heat pump unit 1 continues to heat the water tank 2; in the third stage, based on the first stage, the electric temperature-sensitive valve 7 and the electric temperature-sensitive valve 9 are kept open, and the hot water in the hot water tank 1 and the hot water tank 2 that reaches the first preset value is sent to the heat pump unit 2 by the circulating water pump 2 through the electric temperature-sensitive valve 7, and is converted again by the temperature of the heat pump unit 2. At this time, the electric temperature-sensitive valve 8 is opened first, and the electric temperature-sensitive valve 10 is closed. When the water in the hot water tank 1 reaches the second preset value, the electric temperature-sensitive valve 8 is closed, and the electric temperature-sensitive valve 10 is kept open to continue heating the hot water tank 2. When the water in the hot water tank 2 reaches the second preset value, the solenoid valve 1 and the solenoid valve 2 are opened at the same time. At the same time, the electric temperature-sensitive valve 13, the electric temperature-sensitive valve 18 and the electric temperature-sensitive valve 19 are opened, and the cold water enters the conversion water tank, the water reservoir and the refrigeration unit.

[0037] In the third state, when the system is running at night under low energy consumption conditions and only needs heating but not cooling, the heat stored in the conversion water tank will be released when the system is running under low energy consumption to only meet the heating demand. At this time, electric temperature sensing valve 1, electric temperature sensing valve 2, electric temperature sensing valve 3, electric temperature sensing valve 4, electric temperature sensing valve 5, electric temperature sensing valve 6, electric temperature sensing valve 11 and electric temperature sensing valve 12 are opened. Except for the conversion water tank, hot water tank 1 and hot water tank 2, other equipment remains closed.

[0038] This invention utilizes two heat pump units. One heat pump provides cooling while the condenser water heats two hot water tanks. The other heat pump unit's chilled water cools a transfer tank. The chilled water exchanges heat with a heat exchanger to produce low-temperature cold water at varying temperatures. The condensed water is then heated by a secondary series heat pump to produce hot water. This system fully recovers the low-grade condensation heat of the heat pump units, maximizing waste heat recovery. It also provides both cold and hot water for process production. The transfer tank adjusts the temperature of the combined hot and cold water system to meet the fluctuating heating and cooling needs of various users.

[0039] The present invention discloses a waste heat recovery and energy-saving system for combined cooling and heating. The system uses two heat pump units as low-temperature cooling sources. The condenser of one heat pump unit is set between 45-50°C, cooling and heating two hot water tanks simultaneously. The hot water outlet temperature of the other heat pump unit is set to 60°C. Chilled water is used to cool the conversion tank. After heat exchange with the heat exchanger, low-temperature cold water of different temperatures is obtained. The condensed water outlet is then heated by a secondary series heat pump to obtain hot water. The system fully utilizes the low-grade condensation heat of the heat pump unit to simultaneously supply cold and hot water. A conversion tank and an electric temperature-sensing valve are provided to automatically adjust the hot water temperature of the combined cooling and heating system, thereby meeting the changing cooling and heating demands under various operating conditions. Taking the meat processing production process as an example, the present invention fully considers the dynamic changes in demand for cold water and hot water in production, maximizes the recovery of low-grade waste heat in the process production, and realizes the function of simultaneous supply of cold water and hot water. It not only meets the dynamic changes in energy demand in the production process to ensure continuous and stable production, but also can efficiently utilize low-grade waste heat to improve the overall efficiency of the system, thereby achieving the purpose of energy conservation, emission reduction and lowering production costs.

[0040] Example

[0041] This project is for a broiler chicken production enterprise, and the main process requirements for slaughtering and processing are: hot water (55-60℃) and chilled water (1℃).

[0042] The company slaughters 60,000 chickens a day, and hot and cold water must be produced before 6:30 in the morning; the factory's working hours are 8:00 to 16:30.

[0043] Initial design flow rate: hot water (60℃) 60m 3 / day, cold water (1℃) 100m 3 / day.

[0044] In a waste heat recovery and energy-saving system for combined cooling and heating of the present invention, a first hot water tank, a second hot water tank, a first heat pump unit, a second heat pump unit, a conversion water tank, a shell and tube heat exchanger, a second heat pump unit, a spiral pre-cooling tank, and five circulating water pumps are designed.

[0045] The hot water tank 1 has a water volume of 38m 3 / day, the initial temperature is 12℃, the transition temperature is 45℃ and the maximum temperature is 60℃.

[0046] The water volume of the hot water tank 2 is 28m 3 / day, the initial temperature is 12℃ and the maximum temperature is set at 60℃.

[0047] The heat pump unit 1 has a chilled water outlet temperature of -4.5°C, uses 25% ethylene glycol solution (antifreeze), has a water inlet temperature of 0.5°C, a condensed water inlet temperature of 12°C, and a water outlet temperature of 45°C.

[0048] The conversion water tank has a maximum temperature of 33°C and a water storage capacity of 40m 3 .

[0049] The shell and tube heat exchanger has an inlet water temperature of 1°C.

[0050] The spiral pre-cooling pool requires 100m3 of cold water per day. 3 , as water for slaughter.

[0051] Circulating water pump 7, flow rate 40m 3 / h, lift 18m.

[0052] Circulating water pump 28, flow rate 20m 3 / h, lift 20m.

[0053] Circulating water pump 39, flow rate 20m 3 / h, lift 20m.

[0054] Circulating water pump 410, flow rate 25m 3 / h, lift 32m.

[0055] Circulating water pump 537, flow rate 60m 3 / h, lift 32m.

[0056] The heat pump unit 2 has a condensate inlet temperature of 45°C and an outlet temperature of 60°C.

[0057] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and implementation methods.

[0058] See also Figure 2 The present invention provides an energy-saving system for combined cooling and heating, comprising: a hot water tank 1, a hot water tank 2, a heat pump unit 1, a heat pump unit 2, a conversion water tank 5, a shell and tube heat exchanger 6, a spiral pre-cooling tank 7, a circulating water pump 1, 8; a circulating water pump 2, 9; a circulating water pump 3, 10; a circulating water pump 4, 11; a circulating water pump 5, 12; an electric temperature-sensing valve 1, 13; an electric temperature-sensing valve 2, 14; an electric temperature-sensing valve 3, 15; an electric temperature-sensing valve 4, 16; an electric temperature-sensing valve 5, 17; an electric temperature-sensing valve 6, 18; an electric temperature-sensing valve 7 19; Electric temperature-sensing valve 8 20; Electric temperature-sensing valve 9 21; Electric temperature-sensing valve 10 22; Electric temperature-sensing valve 11 23; Electric temperature-sensing valve 12 24; Electric temperature-sensing valve 13 25; Electric temperature-sensing valve 14 26; Electric temperature-sensing valve 15 27; Electric temperature-sensing valve 16 28; Electric temperature-sensing valve 17 29; Electric temperature-sensing valve 18 30; Electric temperature-sensing valve 19 31; Butterfly valve 1 32; Butterfly valve 2 33; Butterfly valve 3 34; Sight tube 35; Thermometer 36; Solenoid valve 1 37; Solenoid valve 2 38, etc.

[0059] In the present invention, in a specific implementation, the heat pump unit 2 4 is connected to the heat pump unit 1 3 through a water tank.

[0060] In the present invention, in a specific implementation, in the waste heat recovery and energy-saving system for combined cooling and heating, the hot water generated by the heat pump unit 1 3 enters the water tank through the electric temperature-sensing valve 14 and the electric temperature-sensing valve 16, and the heated water enters the heat pump unit 2 4.

[0061] The heat pump unit 2 4 is used to recover the low-grade condensation heat generated by the heat pump unit 1 3.

[0062] In the present invention, in a specific implementation, the waste heat recovery and energy-saving system of the combined cooling and heating system recovers the condensed water produced by the heat pump unit 3, and the outlet temperature is controlled at 45°C.

[0063] In the present invention, in a specific implementation, in the waste heat recovery and energy-saving system of the combined cooling and heating supply, the hot water generated by the heat pump unit 2 4 enters the water tank through the electric temperature sensing valve 20 and the electric temperature sensing valve 22 respectively to obtain high-temperature hot water.

[0064] In the present invention, in a specific implementation, the waste heat recovery and energy-saving system of the combined heat and cold supply, the chilled water side of the heat pump unit 3 is connected with the shell and tube heat exchanger 6, heat exchange obtains 1°C cold water, and supplies it to the spiral pre-cooling tank 7 as low-temperature slaughter water.

[0065] In the present invention, the system further comprises a temperature sensor for measuring the water temperature inside the water tank and a controller for controlling the operation of the system. The controller controls how the system operates according to the temperature information measured by the temperature sensor.

[0066] See also Figure 2 In the present invention, in a specific implementation, in the first state, when the system is running under normal working conditions, in the first stage, tap water is injected into the two water tanks, the electric temperature-sensitive valve 13 is opened, and the electric temperature-sensitive valve 15 is closed. The tap water is sent to the heat pump unit 3 by the circulating water pump 8 through the electric temperature-sensitive valve 13. The tap water is exchanged in the heat pump unit 1 to produce hot water: the electric temperature-sensitive valve 14 and the electric temperature-sensitive valve 24 are opened, and the electric temperature-sensitive valve 16 is closed. The hot water of the first preset value obtained by heat exchange heats the water in the water tank 1, and the excess heat enters the conversion water tank 5. On the cold water side, the cold water at -4.5°C is sent to the shell and tube heat exchanger 6 through the circulating water pump 7. After heat exchange, the cold water at 1°C is supplied to the spiral pre-cooling tank 7.

[0067] In the second stage, the electric temperature-sensing valve 16 is opened and the electric temperature-sensing valve 14 is closed. Other devices maintain the state of the first stage, and the hot water generated by the heat pump unit 1 3 continues to heat the water tank 2 2.

[0068] In the third stage, based on the first stage, the electric temperature-sensitive valve 19 is opened and the electric temperature-sensitive valve 21 is closed. The hot water in the water tank 1 that reaches the first preset value is sent to the heat pump unit 2 4 by the circulating water pump 9 through the electric temperature-sensitive valve 19, and is converted again by the temperature of the heat pump unit 2. At this time, the electric temperature-sensitive valve 20 is opened first, and the electric temperature-sensitive valve 22 is kept closed. When the water in the water tank 1 reaches the second preset value, the electric temperature-sensitive valve 20 is closed and the electric temperature-sensitive valve 22 is opened. When the water in the water tank 2 reaches the second preset value, only the solenoid valve 37 is opened and the solenoid valve 38 is closed. At the same time, the electric temperature-sensitive valves 25, 30, and 31 are opened, and the cold water enters the conversion water tank 5, the water reservoir, and the refrigeration unit.

[0069] In the present invention, in the second state, when the system is running under the condition of increased production demand, the two water tanks operate simultaneously. In the first stage, tap water is injected into the two water tanks, the electric temperature-sensitive valve 13 is opened, and the electric temperature-sensitive valve 15 is opened. The water in the two water tanks is sent to the heat pump unit 3 by the circulating water pump 8 through the electric temperature-sensitive valves 13 and 15. The tap water is exchanged in the heat pump unit 1 to produce hot water. On the hot water side: the electric temperature-sensitive valves 14 and 24 are opened, and the first hot water obtained by heat exchange and the preset value first heats the water in the water tank 1. On the cold water side, the cold water at -4.5°C is sent to the shell and tube heat exchanger 6 through the circulating water pump 8, and the cold water at 1°C is obtained by heat exchange to supply the spiral pre-cooling pool 7.

[0070] In the second stage, the electric temperature-sensing valve 16 is opened and the electric temperature-sensing valve 14 is closed. Other devices maintain the state of the first stage, and the hot water generated by the heat pump unit 1 3 continues to heat the water tank 2 2.

[0071] In the third stage, based on the first stage, the electric temperature-sensitive valve seven 19 and the electric temperature-sensitive valve seven-nine 21 are kept open, and the hot water in the two water tanks that reaches the first preset value is sent to the heat pump unit two 4 by the circulating water pump 9 through the electric temperature-sensitive valve 19, and is converted again by the temperature of the heat pump unit two. At this time, the electric temperature-sensitive valve 20 is opened first, and the electric temperature-sensitive valve 22 is kept closed. When the water in the water tank one 1 reaches the second preset value, the electric temperature-sensitive valve 20 is closed, and the electric temperature-sensitive valve 22 is kept open. When the water in the water tank two 2 also reaches the second preset value, the solenoid valve 37 and the solenoid valve 38 are opened at the same time. At the same time, the electric temperature-sensitive valve thirteen 25, the electric temperature-sensitive valve eighteen 30, and the electric temperature-sensitive valve nineteen 31 are opened, and the cold water enters the conversion water tank 5, the water reservoir, and the refrigeration unit.

[0072] See also Figure 3In the present invention, in the third state, when the system is running under low energy consumption conditions at night, and only heat is needed without cooling, the heat stored in the conversion water tank 5 will be released when the system is running under low energy consumption, only meeting the heating demand. At this time, the electric temperature sensing valve 1 13, the electric temperature sensing valve 2 14, the electric temperature sensing valve 3 15, the electric temperature sensing valve 4 16, the electric temperature sensing valve 5 17, the electric temperature sensing valve 6 18, the electric temperature sensing valve 11 23, and the electric temperature sensing valve 12 24 are opened. Except for the conversion water tank 5, the hot water tank 1 and the hot water tank 2, other equipment remains closed.

[0073] In order to clearly understand this system, the following analysis is based on the actual operation of the enterprise.

[0074] Preliminary calculations indicate a daily requirement of 60 tons of hot water. To ensure system stability, two water tanks are used: hot water tank 1 and water heat tank 2, with a total storage capacity of 60 tons. Utilizing the nighttime peak-valley electricity price, calculations show that heat pump unit 1 and the shell-and-tube heat exchanger can generate 1°C of cold water within a certain period of time, meeting production requirements before the 6:30 AM start date. While heat pump unit 1 produces cold water, the hot water generated by heat pump unit 1 heats the water in water tank 1 to 45°C. Once this temperature is reached, heat pump unit 1 becomes inefficient and unstable. At this point, electric thermostatic valves 2 and 4 receive a command to automatically switch to hot water tank 2. The starting temperature of hot water tank 2 is 12°C, and the water gradually heats up. The hot water tank outlet is connected to an external location where hot water is needed. In actual operation, hot water tank 1 can basically meet the heat requirement after heating, so hot water tank 2 can be used as a backup heat dissipation space.

[0075] Heat pump unit 3 can be considered a low-temperature refrigeration unit, but it also generates heat. Based on equipment selection and calculation, the chilled water temperature on one side is set to -4.5°C, the supply water temperature is 0.5°C, and the maximum outlet water temperature on the other side is set to 45°C. The generated hot water heats the water in tank 1, gradually raising the temperature to 45°C. The 45°C hot water in tank 1 then enters heat pump unit 2 4 for heat exchange, generating hot water through temperature conversion. Heat pump unit 3 then exchanges heat with a shell-and-tube heat exchanger on the other side, producing 1°C cold water for use in slaughter.

[0076] Heat pump unit 2 (4) can be considered a high-temperature heating unit. It first heats water tank 1 (1). After heat pump unit 1 (3) heats the water from 12°C to 45°C, heat pump unit 2 (4) continues to heat water tank 1 (1). As heat pump unit 2 (4) heats water tank 1 (1), the initial temperature rises from 12°C to 45°C. Heating continues to 60°C. The difference between 12°C and 45°C is the condensation heat recovered by heat pump unit 2, effectively recovering low-grade waste heat energy. When water tank 1 reaches 60°C, electric temperature control valves 8 (20) and 10 (22) automatically switch to heat hot water tank 2 (2). On the cold water side, the cold water has three destinations: storage in the transfer tank 5, discharge to the cold water reservoir, or discharge to the well.

[0077] When one side is cooling, the other side needs to release heat, and when one side releases heat, the other side also needs to absorb heat. Although the two heat pump units can assist each other, they are not necessarily completely matched and balanced. Therefore, a conversion water tank 5 is added to the system, and the maximum temperature of the conversion water tank 5 is set to 33°C, and the water storage capacity is 40m3. 3 In this example, if heat pump unit 1 has absorbed sufficient heat from water tank 1 and water tank 2 2 during heat release, the remaining heat can be discharged first to conversion tank 5 and then released when needed at night. If conversion tank 5 reaches its maximum temperature limit, the remaining heat is ultimately discharged into the well.

[0078] In summary, compared with the prior art, the present invention provides a waste heat recovery and energy-saving system for combined heat and cold supply, in which the heat pump unit 1 obtains cold water by heat exchange with a shell and tube heat exchanger, and recovers the condensation heat through the heat pump unit 2. The 60°C hot water obtained by conversion can be cooled by cooling water, and the condensation temperature of the refrigeration unit can be controlled at 45°C, which can improve the energy efficiency (coefficient of performance COP) of the heat pump unit. It not only maximizes the recovery and utilization of the low-grade condensation heat of the heat pump unit, improves the overall efficiency of the energy supply system, and has significant energy-saving benefits, but also can meet the cooling and heating needs of production at the same time, and dynamically adjust according to different working conditions, which is conducive to ensuring continuous and stable process production.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A waste heat recovery and energy-saving system for combined cooling and heating, characterized in that: include: Hot water tank 1, hot water tank 2, heat pump unit 1, heat pump unit 2, conversion water tank, shell and tube heat exchanger and spiral pre-cooling pool; wherein, the first outlet of the hot water tank 1 is connected to the first inlet of the heat pump unit 1 through the electric temperature-sensing valve 1 and the circulating water pump 1, and the first outlet of the heat pump unit 1 is connected to the first inlet of the hot water tank 1 through the electric temperature-sensing valve 2; the second outlet of the hot water tank 1 is connected to the first inlet of the heat pump unit 2 through the electric temperature-sensing valve 7 and the circulating water pump 2, and the first outlet of the heat pump unit 2 is connected to the second inlet of the hot water tank 1 through the electric temperature-sensing valve 8; the first outlet of the hot water tank 2 is connected to the first inlet of the heat pump unit 1 through the electric temperature-sensing valve 3 and the circulating water pump 1, and the heat pump unit The first outlet of group one is connected to the first inlet of hot water tank two through electric temperature-sensitive valve four; the second outlet of hot water tank two is connected to the first inlet of heat pump unit two in sequence through electric temperature-sensitive valve nine and circulating water pump two, and the first outlet of heat pump unit two is connected to the second inlet of hot water tank two through electric temperature-sensitive valve ten; the second outlet of heat pump unit one is connected to the first inlet of shell and tube heat exchanger through circulating water pump four, and the first outlet of shell and tube heat exchanger is connected to the second inlet of heat pump unit one; the second outlet of heat pump unit two is connected to the first inlet of conversion water tank through electric temperature-sensitive valve thirteen, and the first outlet of conversion water tank is connected to the second inlet of heat pump unit two in sequence through electric temperature-sensitive valve fourteen and circulating water pump five; The second outlet of the conversion water tank is connected to the first inlet of the hot water tank one through the electric temperature-sensing valve 12 and the electric temperature-sensing valve 2 in sequence; the second outlet of the conversion water tank is connected to the first inlet of the hot water tank two through the electric temperature-sensing valve 12 and the electric temperature-sensing valve 4 in sequence; the second inlet of the conversion water tank is connected to the first outlet of the hot water tank one through the electric temperature-sensing valve 11 and the electric temperature-sensing valve 1; the second inlet of the conversion water tank is connected to the first outlet of the hot water tank two through the electric temperature-sensing valve 11 and the electric temperature-sensing valve 3 in sequence.

2. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 1 is characterized in that: The tops of the hot water tanks 1 and 2 are both equipped with electromagnetic valves for controlling the internal pressure of the water tanks.

3. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 1 is characterized in that: It also includes a temperature sensor for measuring the water temperature inside the water tank and a controller for controlling the operation of the system. The controller controls the operation mode of the waste heat recovery and energy-saving system according to the temperature information measured by the temperature sensor.

4. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 3 is characterized in that: The hot water generated by heat pump unit 1 enters hot water tank 1 through electric temperature-sensitive valve 2, and the hot water generated by heat pump unit 1 enters hot water tank 2 through electric temperature-sensitive valve 4. The heated water in hot water tank 1 and hot water tank 2 enters heat pump unit 2.

5. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 4 is characterized in that: When the water temperature in the hot water tank 1 is equal to or greater than a first preset value, the electric temperature-sensing valve 4 is opened, the electric temperature-sensing valve 2 is closed, and other devices always remain in the open state.

6. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 1 is characterized in that: The hot water generated by the heat pump unit 2 enters the hot water tank 1 through the electric temperature-sensitive valve 8, and the hot water generated by the heat pump unit 2 enters the hot water tank 2 through the electric temperature-sensitive valve 10 to obtain high-temperature hot water.

7. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 5, characterized in that: When the water temperature in hot water tank 1 is equal to or greater than the second preset value, the solenoid valve 1 connecting hot water tank 1 to industrial water is opened, the solenoid valve 2 connecting hot water tank 2 to industrial water is opened, and other devices always remain in the open state.

8. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 7, characterized in that: In the first state, when the system is running under normal working conditions, in the first stage, tap water is injected into hot water tank 1 and hot water tank 2, electric temperature-sensitive valve 1 is opened, electric temperature-sensitive valve 3 is closed, and tap water is sent to heat pump unit 1 by circulating water pump 1 through electric temperature-sensitive valve 1. Tap water is exchanged in heat pump unit 1 to produce hot water. On the hot water side: electric temperature-sensitive valve 2 and electric temperature-sensitive valve 12 are opened, electric temperature-sensitive valve 4 is closed, and the hot water of the first preset value obtained by heat exchange heats the water in water tank 1, and the excess heat enters the conversion water tank. On the cold water side, -4.5℃ cold water is sent to the shell and tube heat exchanger through circulating water pump 1, and the cold water obtained by heat exchange is 1℃, which is supplied to the spiral pre-cooling pool; in the second stage, electric temperature-sensitive valve 4 is opened, electric temperature-sensitive valve 2 is closed, and other equipment Maintaining the state of the first stage, the hot water generated by the heat pump unit 1 continues to heat the water tank 2; in the third stage, based on the first stage, the electric temperature-sensitive valve 7 is opened and the electric temperature-sensitive valve 9 is closed. The hot water in the hot water tank 1 that reaches the first preset value is sent to the heat pump unit 2 by the circulating water pump 2 through the electric temperature-sensitive valve 7, and is converted again by the temperature of the heat pump unit 2. At this time, the electric temperature-sensitive valve 8 is opened first, and the electric temperature-sensitive valve 10 is kept closed. When the water in the hot water tank 1 reaches the second preset value, the electric temperature-sensitive valve 8 is closed, the electric temperature-sensitive valve 9 and the electric temperature-sensitive valve 10 are opened, the solenoid valve 1 is opened, and the solenoid valve 2 is closed. At the same time, the electric temperature-sensitive valves 13, 18, and 19 are opened, and the cold water enters the conversion water tank, the water reservoir, the refrigeration unit 1, and the refrigeration unit 2.

9. A waste heat recovery energy-saving system for combined cooling and heating according to claim 7, characterized in that: In the second state, when the system is running under the condition of increased demand, hot water tank 1 and hot water tank 2 are running at the same time. In the first stage, tap water is injected into hot water tank 1 and hot water tank 2, electric temperature-sensing valve 1 is opened, electric temperature-sensing valve 3 is opened, and the water in hot water tank 1 and hot water tank 2 is sent to heat pump unit 1 by circulating water pump 1 through electric temperature-sensing valve 1 and electric temperature-sensing valve 3. Tap water is exchanged in heat pump unit 1 to produce hot water. On the one side: electric temperature-sensing valve 2 and electric temperature-sensing valve 12 are opened, and electric temperature-sensing valve 4 is closed. The hot water of the first preset value obtained by heat exchange first heats the water in hot water tank 1. On the cold water side, cold water of -4.5℃ is sent to the shell and tube heat exchanger through circulating water pump 1, and cold water of 1℃ is obtained through heat exchange to supply the spiral pre-cooling pool. In the second stage, electric temperature-sensing valve 4 is opened, electric temperature-sensing valve 2 is closed, and other equipment is kept Maintaining the state of the first stage, the hot water generated by the heat pump unit 1 continues to heat the water tank 2; in the third stage, based on the first stage, the electric temperature-sensitive valve 7 and the electric temperature-sensitive valve 9 are kept open, and the hot water in the hot water tank 1 and the hot water tank 2 that reaches the first preset value is sent to the heat pump unit 2 by the circulating water pump 2 through the electric temperature-sensitive valve 7, and is converted again by the temperature of the heat pump unit 2. At this time, the electric temperature-sensitive valve 8 is opened first, and the electric temperature-sensitive valve 10 is closed. When the water in the hot water tank 1 reaches the second preset value, the electric temperature-sensitive valve 8 is closed, and the electric temperature-sensitive valve 10 is kept open to continue heating the hot water tank 2. When the water in the hot water tank 2 reaches the second preset value, the solenoid valve 1 and the solenoid valve 2 are opened at the same time. At the same time, the electric temperature-sensitive valve 13, the electric temperature-sensitive valve 18 and the electric temperature-sensitive valve 19 are opened, and the cold water enters the conversion water tank, the water reservoir and the refrigeration unit.

10. The waste heat recovery and energy-saving system for combined cooling and heating according to claim 7, characterized in that: In the third state, when the system is running at night under low energy consumption conditions and only needs heating but not cooling, the heat stored in the conversion water tank will be released when the system is running under low energy consumption to only meet the heating demand. At this time, electric temperature sensing valve 1, electric temperature sensing valve 2, electric temperature sensing valve 3, electric temperature sensing valve 4, electric temperature sensing valve 5, electric temperature sensing valve 6, electric temperature sensing valve 11 and electric temperature sensing valve 12 are opened. Except for the conversion water tank, hot water tank 1 and hot water tank 2, other equipment remains closed.

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