Expert: heating system on the amount of heat regulation technology - heating, heating - HVAC Industry
Harbin Institute of Technology: Jiangyong Cheng, Kao Hui-Na, Gu Dongming, Zhengrui Yun, Wang Zhaojun, side in harmony, Zhao Hua
Abstract: Heating Terminal adjustable heat, heat the user fees in accordance with the heat after the indoor heating system has become a self-regulating system. Must be adjusted using the corresponding heating program, according to the user to achieve the necessary heat for heating the heating system Energy . Achieve energy-saving technology the system is reflected in three aspects, first the user to achieve on-demand hot buy hot; second conveyor system to minimize energy consumption means the energy delivery to the user; third heat in the heat required to ensure the user is always in the best context good combustion state. In all three to achieve the best technology is the key heating appropriate adjustments.
1, Overview Heating heating metering and charging the user to implement [1] After the heat must have the appropriate means of adjustable, or bring about a genuine energy saving. Users can adjust the heat current to achieve the technology mainly in the interior of each user Radiator Install Self-supporting pipe temperature control valve, the user can personal habits and economic conditions in regulating valve to set the desired temperature. Valve installation and adjustment methods are mainly two-way valve and three-way valve in two ways, two ways for this heating system should also take appropriate regulatory programs.
2, Thermal Operation Analysis 2.1 User Analysis 2.1.1 installed indoor two-way valve system
Each radiator is equipped with a self-dual pass Thermostatic valve Figure 1 (a) shows, this system is suitable for indoor levels of household heating systems. Double-pass temperature control valve, the indoor heating system has become a variable flow system. According to fluid friction resistance due to energy loss caused by the availability of:
(1) where: for, return water pressure; fluid density; friction coefficient; pipe diameter; for, Backwater average velocity. Transform (1) type can be: (2). Where: is for, return pressure difference; is the local resistance coefficient; is the supply and return water flow. According to the operation of indoor heating systems combined with (2)-type analysis, we can see changes in supply and return water flow in the active regulation of the user system, and is in active regulation changes after the local resistance coefficient. Changes in supply and return water pressure depends on heat cycle network Pump Operating state, constant speed circulation pump run-time changes in small, variable speed circulation pump will be more run-time changes.
2.1.2 installed three-way valve in the indoor system Each radiator is equipped with a thermostatic valve Self-three links in Figure 1 (b) shows, this system is suitable for indoor vertical system, also apply to indoor levels of household heating systems. Thermostatic valve with three links, the indoor heating system changed very little traffic, can be considered a constant flow system. But to have some hot water directly back into the hot water pipes network, resulting in some energy waste.
The following system for the above two indoor heat regulation scheme of the thermal network analysis of operating conditions.
2.2 Thermal network analysis Transport heat circulation pump to run the program by two discussions, one is the constant speed operation, the other is the variable speed operation. Circulation pump running programs and indoor operation of the system will produce four kinds of combination programs to run the program.
2.2.1 Indoor system with variable flow constant speed circulation pump Indoor system with variable flow operation, constant speed circulation pump to run. As the resistance changes in indoor radiator thermostatic valve, the tube network
Fund Project: National "Eleventh Five-Year" key scientific and technological projects. Resistance of change, allowing the flow of heat network changes, the amount is too hot for the net change in drag coefficient, circulation pump head will increase exports. Clearly the work of the system is working along the pump
Characteristic curve, and at the lowest heat load heat network traffic may become very small, it can withstand heat flow is too small to conduct a comprehensive analysis of need.
Another perspective from the energy-saving, constant speed pump flow rate decreases in the circulation pump, the motor's load becomes smaller, its consumption of electrical energy will be reduced. Reference [2] gives the throttle adjustment when the centrifugal pump load Motor Input power formula example is shown below:
(3) where: is the flow too circulating pump motor power consumption is the circulation pump rated flow, is the circulating pump motor power rating. By (3) type could be the launch of its energy-saving rate of the formula (4) Type:
(4) where: is the flow of circulation pump motor is too power-saving power. According to (4)-type flow rate calculated several energy-saving rate of pump motor, when the saving rate; time, the saving rate.
Such programs is also energy efficient, but the smaller the flow of energy saving effect is not obvious, theoretically saving the time of zero flow rate 0.55.
2.2.2 Indoor system with variable flow variable speed circulation pump Indoor system with variable flow operation, circulation pump variable speed operation. After the indoor radiator temperature control valve to change its resistance, the resistance characteristics of the tube network change, making changes in the flow of heating network, shown in Figure 2. At this time circulation pump speed should be changed so that the work characteristics of the parallel circulation pump down, the best operating point down the tube network should be returned to the point of resistance characteristics, as shown in Figure 3. Such regulation also exists in the system program minimum flow constraints.
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