The Thermostat Control System Design For Direct Thermal Air Source Water Heater

Air source water heater, also been called heat pump water heater, is the development direction of a new generation of electric water heaters. This type of water heater heat exchange by the evaporator or condenser, it constantly xtraction or release of heat through the circulatory system. Transfer energy to the water tank or buildings, meet with the demand of the user for domestic hot water, warm or air conditioning.Compared with ordinary gas water heater and solar water heaters, this type of water heater has been widely used in the developed world for its energy-saving, environmentally friendly, efficient defrosting, convenience and comfort, low noise, etc.But there are some drawbacks exist in this type of water heater. Water temperature fluctuations, hot water comes slow, hot water difficulty in cold regions mainly exists in this type of water heater. To solve these problems we designed a temperature control system with optimized PID control. Establishment a mathematical model of the temperature control based on the analysis of water flow, Water pressure and Income water temperature. According to gather temperature data establish the rate of change of temperature control model. By analysis the diffident relationship among valve opening angle, the temperature set by the Users, Water flow, establish a mathematical model of valve opening. The thermostatically controlled temperature adjustment range is-35 ~ + 85 ℃, the steady-state temperature control accuracy of 2 ℃, it finally applied to a certain type of direct thermal air heater products, with the advantages of fast, stable, non-volatility of thermostatic water.