CN102997443B - Optimal control method for heat pump-gas water heater combination - Google Patents

Abstract

The invention relates to an optimal control method for a heat pump-gas water heater combination. The method is characterized by comprising the following steps that a user inputs a local electricity price and a local gas price through an input module, and sets water consumption peak time t1, an upper limit water temperature T3 and a lower limit water temperature T4; a heat pump system detects in real time, and collects the temperatures of an outdoor ambient temperature sensor T1 and a water tank temperature sensor T2 through a temperature collector; a processor automatically computes total power consumption needed for running the heat pump system and optimal startup time t2, and computes needed total power consumption cost and the like according to the total power consumption needed for running the heat pump system and the local electricity price; when the water tank temperature T2 reaches the upper limit water temperature T3, the heat pump system stops running; and after the heat pump system stops running and when the water tank temperature T2 falls to the set lower limit temperature T4 of a water tank due to natural heat dissipation or the use of a small amount of water before the set water consumption peak time, the heat pump system is started up automatically till the set upper limit water temperature T3 of the water tank is reached. The heat pump system can run at a time interval when the efficiency is highest all the day, so that a better energy-saving effect is achieved.

Description

Optimal control method for combination of heat pump and gas water heater

technical field

The invention relates to an optimal control method for the combination of a heat pump and a gas water heater.

Background technique

Heat pump water heaters are widely used in production and domestic hot water supply due to their advantages of energy saving, environmental protection and safety. However, one of the main problems faced in the application of heat pump water heaters is: when the ambient temperature is low, the heat supply is insufficient and the energy efficiency ratio decreases. In order to solve the problem of insufficient heat supply, one of the main measures taken at present is the gas auxiliary heating method.

At present, the main mode of operation control of the gas-assisted heat pump hot water system is: after the user sets the operating temperature of the heat pump water heater, the heat pump water heater is always in standby mode. When the temperature of the water tank of the heat pump water heater is lower than the set temperature, the heat pump water heater runs. When the set temperature is reached, the heat pump water heater stops running. When the user uses hot water, if the temperature of the water tank does not reach the set temperature, the gas water heater is turned on for heating. There are two problems with this control method: one is that due to the large change in the outdoor ambient temperature throughout the day, the energy efficiency ratio of the heat pump water heater in different temperature time periods is greatly different. The energy efficiency when operating in the temperature period is about 30% higher than that in the lowest temperature period. Obviously, the above control method cannot make the heat pump water heater operate in the time period with the highest energy efficiency every day, and its energy-saving effect needs to be further improved; It is because the energy efficiency ratio of the air source heat pump varies greatly throughout the year, and when the energy efficiency ratio of the heat pump is lower than 2.5, it is more economical to directly use gas heating. Obviously, the above control method needs to be improved in terms of operating economy.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide an energy-saving control method for the combination of a heat pump and a gas water heater, which can select the heating energy mode of the water heater and the optimal opening time according to the set temperature of the water heater, the actual temperature of the water tank and the outdoor ambient temperature Section, so that the water heater is in an economical and efficient operating state.

In order to achieve the above object, the present invention is achieved in this way, which is an optimal control method for the combination of a heat pump and a gas water heater, characterized in that the steps are as follows:

(a) When the combined water heater is powered on, the user inputs the local electricity price and gas price through the input module, and sets the peak water consumption time t1, the upper limit temperature T3 and the lower limit temperature T4 of the water temperature;

(b) The heat pump system detects in real time and collects the temperature values of the outdoor ambient temperature sensor T1 and the water tank temperature sensor T2 through the temperature collector;

(c) The microprocessor calculates the total heat required for heating according to the water upper limit temperature T3 and the current water tank temperature T2;

(d) The microprocessor automatically calculates the total power consumption required to run the heat pump system based on the built-in outdoor ambient temperature-time function relational expression and the relational expression of the heat pump water heater’s instantaneous heating capacity, energy efficiency ratio, outdoor ambient temperature, and actual temperature of the water tank And the best opening time t2;

(e) The microprocessor calculates the total cost of electricity required to operate the heat pump system based on the total electricity consumption required to operate the heat pump system and the local electricity price;

(f) The microprocessor automatically calculates the total gas consumption required for running gas heating, and then calculates the total gas cost required according to the local gas price;

(g) the microprocessor compares the economics of running a heat pump system for heating versus a gas system for heating;

(h) If it is more economical to run the heat pump system for heating, when the time reaches the optimal turn-on time t2 of the heat pump system, the microprocessor outputs a signal to run the heat pump system, and the heat pump system starts to run;

(i) When the water tank temperature T2 reaches the set temperature upper limit temperature T3, the heat pump system stops running;

(j) After the heat pump system stops running, when the temperature T2 of the water tank drops to the lower limit temperature T4 of the set temperature of the water tank due to the natural heat dissipation of the water tank or a small amount of water used before the peak water use time, the heat pump system (3) will automatically start until it reaches the set temperature of the water tank. Set temperature upper limit temperature T3;

(k) If it is more economical to run the gas system for heating, the gas system is directly turned on for heating when the user uses it.

When the microprocessor calculates that it is more economical to run the heating of the gas system, it can also adopt the control method of combining the heat pump system and the two-stage heating of the gas system, and the control steps are as follows:

(a) When the microprocessor calculates that it is more economical to run the gas system for heating, it can further calculate the highest intermediate water tank temperature T5 that can be achieved by the heat pump system, which is relatively economical for gas system heating;

(b) The microprocessor calculates the optimal opening time t3 of the heat pump system when the highest intermediate water tank temperature T5 is reached;

(c) When the time reaches the optimal turn-on time t3 of the heat pump system, the microprocessor outputs a signal to run the heat pump system, and the heat pump system starts to run;

(d) When the water tank temperature T2 reaches the highest intermediate water tank temperature T5, the heat pump system stops running;

(e) When the user is in use, directly turn on the gas system to further heat the hot water at the temperature of the water tank to the required temperature.

The input module is a keyboard or a touch screen.

Compared with the prior art, the present invention has the following advantages:

(1) The combined water heater can automatically compare the economical efficiency of running heat pump system heating and gas heating, so that the water heater is in an economical operating state.

(2) The heat pump system can automatically calculate the optimal operating time period and start automatically, so that the heat pump system can operate at the time period with the highest energy efficiency throughout the day, so the energy saving effect is better.

Description of drawings

Fig. 1 is a block diagram of the control principle implemented by the present invention.

Detailed ways

Embodiments of the invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

As shown in Figure 1, it is an optimal control method for the combination of a heat pump and a gas water heater, characterized in that the steps are as follows:

(a) When the combined water heater is powered on, the user inputs the local electricity price and gas price through the input module 5, and sets the peak water consumption time t1 (t1 is generally a certain moment within 16:00-24:00), the upper limit temperature of water temperature T3 and Water temperature lower limit temperature T4;

(b) The heat pump system detects and collects the temperature values of the outdoor ambient temperature sensor T1 and the water tank temperature sensor T2 through the temperature collector 1 in real time;

(c) The microprocessor 2 calculates the total heat required for heating according to the water upper limit temperature T3 and the current water tank temperature T2 (before 10:00);

(d) The microprocessor 2 automatically calculates the total power consumption required for running the heat pump system 3 according to the built-in outdoor ambient temperature-time function relational expression and the relational expression of the instantaneous heating capacity of the heat pump water heater, the energy efficiency ratio, the outdoor ambient temperature, and the actual temperature of the water tank amount and the optimal opening time t2;

(e) The microprocessor 2 calculates the total electricity consumption cost according to the total electricity consumption required to run the heat pump system 3 and the local electricity price;

(f) Microprocessor 2 automatically calculates the total gas consumption required for running gas heating, and then calculates the total gas cost required according to the local gas price;

(g) Microprocessor 2 compares the economics of running heat pump system 3 heating and gas system 4 heating;

(h) If it is more economical to run the heat pump system 3 for heating, when the time reaches the optimal turn-on time t2 of the heat pump system 3, the microprocessor 2 outputs a signal to run the heat pump system, and the heat pump system 3 starts to run;

(i) When the water tank temperature T2 reaches the set temperature upper limit temperature T3, the heat pump system 3 stops running;

(j) After the heat pump system 3 stops running, when the temperature T2 of the water tank drops to the lower limit temperature T4 of the set temperature of the water tank due to the natural heat dissipation of the water tank or a small amount of water used before the set peak water consumption time, the heat pump system 3 will automatically start until it reaches the set temperature of the water tank. Temperature upper limit temperature T3;

(k) If it is more economical to run the gas system 4 for heating, then directly turn on the gas system for heating when the user uses it.

In this embodiment, when the microprocessor 2 calculates that it is more economical to run the gas system 4 for heating, it can also adopt a control method combining the heat pump system 3 and the gas system 4 for two-stage heating, and the control steps are as follows:

(a) When the microprocessor 2 calculates that it is more economical to run the gas system 4 for heating, it can further calculate the highest intermediate water tank temperature T5 that can be achieved by the heat pump system 3 that is economical to heat the gas system 4;

(b) The microprocessor 2 calculates the optimal opening time t3 of the heat pump system 3 when the highest intermediate water tank temperature T5 is reached;

(c) When the time reaches the optimal turn-on time t3 of the heat pump system 3, the microprocessor 2 outputs a signal to run the heat pump system 3, and the heat pump system 3 starts to run;

(d) When the water tank temperature T2 reaches the highest intermediate water tank temperature T5, the heat pump system 3 stops running;

(e) When the user uses it, the gas system 4 is directly turned on to further heat the hot water with a temperature of T5 in the water tank to the required temperature.

In this embodiment, the input module 5 is a keyboard or a touch screen.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (2)

1. an optimal control method for heat pump and gas heater combination, is characterized in that step is as follows:

(a) in the time that combination of water heater is switched on, user inputs local electricity price and gas price by input module (5), sets water use peak time t1, water ceiling temperature T3 and water temperature lower limit temperature T4;

(b) heat pump detects and passes through Temperature sampler (1) and collect the temperature of outdoor environment temperature sensor T1 and water tank temperature sensor in real time;

(c) microprocessor (2), according to water ceiling temperature T3 and current water tank temperature T2, calculates the required total amount of heat of heating;

(d) microprocessor (2), according to the relational expression of built-in outdoor environment temperature-time function relation formula and the instantaneous heating capacity of Teat pump boiler, Energy Efficiency Ratio and outdoor environment temperature, water tank actual temperature, calculates the required total electricity consumption of operating heat pump system (3) and best opening time t2 automatically;

(e) microprocessor (2) calculates required electricity consumption totle drilling cost according to the required total electricity consumption of operating heat pump system (3) and local electricity price;

(f) microprocessor (2) automatically calculates operating gas and heats the total consumption of required combustion gas, then calculates required combustion gas totle drilling cost according to local gas price;

(g) microprocessor (2) economy that relatively operating heat pump system (3) heats and gas burning system (4) heats;

(h) as operating heat pump system (3) heat more economical, in the time that the time arrives the best opening time t2 of heat pump (3), microprocessor (2) output operating heat pump system signal, heat pump (3) brings into operation;

(i) current water tank temperature T2 arrives while setting water ceiling temperature T3, and heat pump (3) is out of service;

(j) after heat pump (3) is out of service, when due to water tank natural heat dissipation or before setting the water use peak time, a small amount of water causes current water tank temperature T2 to be reduced to water temperature lower limit temperature T4, heat pump (3) is opened automatically, until reach water ceiling temperature T3;

(k) as operating gas system (4) heats more economically, in the time that using, user directly opens gas burning system heating.

According to right 1 according to the optimal control method of described heat pump and gas heater combination, it is characterized in that described input module (5) is keyboard or touch-screen.