Fitting Curve of Circulating Water Pump and Its Practical Application

Hot water heating system is a complex system of hot users, heat network and heat source and circulating water pump. In order to enable the circulating water pump put into operation in the high-efficiency area, and make the circulating water volume meet the need, without causing serious water and heat imbalance, we must analyze the circulation pump (single or multiple) operating in the system status . The result is a system that matches the system's circulating water pump to the maximum possible "full load, high efficiency" operation. Using the drawing method and the difference method to determine the pump performance parameters and operating points to select the matching pump, the accuracy is poor, and more troublesome; Therefore, using the principle of least squares method for heating circulating pump performance experimental data curve fitting, Discuss the working condition of circulating pump again. A circulating pump curve fitting In this paper, the least square method to polynomial curve fitting to find the circulating pump performance curve equation. The basic idea is to set up the error equation through error analysis, to derive the corresponding normal equations under the condition of the smallest error, to obtain the regression coefficient (least squares estimation) by solving the normal equations (linear algebraic equations) Set up a curve fitting polynomial. 2 Applied Research In the previous section, we introduced the curve fitting equation of pump performance solved by the numerical method. Knowing this equation, we can easily know the operation of the pump. If we give the equation of pipeline characteristic and solve them in series, calculate the working point and get the flow and lift of the working point, then we can compare with the total flow and total resistance of the actual pipeline to analyze the system hydraulic conditions , Come to match the pump to determine the solution to the hydraulic imbalance. The examples given in this section are fully analyzed. 2.1 System Overview Known a heating system, the building area of ​​90,000 m2. The estimated heat load is 5.2MW, the total system water supply temperature is 95 ℃, the return water temperature is 70 ℃, the network heat dissipation and leakage coefficient K is 1.05, and the flow additional coefficient φ is 1.2. The heating radius L is 500m, the friction resistance R is 70 Pa / m, the percentage of local resistance loss relative to the distance takes a as 0.3, the internal resistance of heat source Hr is 10X104Pa, the user system resistance Hy is 1x104Pa, the margin coefficient K is 1.15. 2.2 Analysis of system conditions Therefore, for a serious hydraulic imbalance in heating systems, especially end users is not hot, can not simply use the method to increase the pump to solve. Since the operating point of a single pump is already in the flat area of ​​the pump performance curve, the total flow increase is limited after the pump is increased. If there are two pumps running in parallel, the synthetic curve is more flat, and then add a pump running in parallel, the total flow increase will be smaller or not increase. Therefore, to solve the problem of hydraulic imbalance in heating system, we should first consider adjusting the pipe network through the hot user inlet valve so that the system flow can be rationally distributed. Of course, if the total flow does not meet the requirements, a single pump that matches the system or a combination of more than one pump that makes the pump work in the high-efficiency area should be selected or calculated. 3 Conclusion (1) For an expansion system, with the increasing number of hot users, the original pump has been small, through the pump performance analysis, the use of multiple pumps parallel operation is possible. However, what we often encounter is that the flow and lift of a single pump far exceed the actual needs of a single pump. Due to the imbalance of the network, there are always some users are not hot, in order to make up for the defects brought by the imbalance, the use of multiple pumps in parallel operation. At this point the system of circulating water has increased, but the added value is very small, the pump efficiency is naturally low. (2) Due to the serious hydraulic imbalance in the network, the pump can not meet the needs of end users after it is connected in parallel. Even replacing high-power and large-flow pumps is of no avail. In fact, if the hydraulic imbalance in the network is serious, as long as the performance of the pipeline is unchanged, the traffic will maintain the same degree of mismatch after the traffic increases. (3) The analysis of hydraulic conditions is the key to understand the operation of the entire system, and the establishment of circulating pump performance curve equation for the hydraulic conditions of great convenience. Circulating pump performance curve equation for the computer to choose a circulating water pump laid the theoretical foundation, but also to achieve the basis of quantitative management

Other Door Accessories

Sectional Door Accessories: motor 220V-380V, control box, spring break device, cable break device , aluminum alloy rope pulley, enhanced shaft bracket, air bag system, duplex enhanced guide wheel bracket.

Detail introduction for above main accessories

1.Motor and controller:

The garage door operator is designed for residential overhead sectional and tilt doors.

The operator memorizes the limit positions and unique braking system that slows the unit down at the end of its travel.

Rolling code remote control with max. 20 pcs hand transmitters.

The operator is equipped with a manual release lever which allows manual operation of the door in case of power failure.

The controller has a security LOCK function which prevents operation of the door from transmitter.

2.spring break device:

Sectional doors are hinged and they bend in the tracks as the door opens and closes. Many of these doors are counterbalanced with extension springs, also designated "stretch springs," and they have seven characteristics. The length is the measurement of all the coils pressed together. This, along with the inside diameter of the coils and wire size - the thickness of the wire from which the springs are made - determine the stretch, the distance the spring is extended - normally half the door height, and pull, the force the spring pulls when stretched its normal length. The type of ends determine how the ends of the spring are mounted. The initial tension is the percentage of pull needed to separate the coils. This is determined by the pitch with which the springs are wound. On sectional garage door springs this is normally 15 percent. For example a 100 pound pull spring requires 15 pounds of weight to separate the coils; when a door is open the two springs will support 15 pounds of door weight without any stretch.

Most extension springs are made of oil tempered wire. These are normally coated or painted. Some springs are made of galvanized wire.

3.able break device:

cable break device ,door hardware

adjustable bottom bracket .

the raw material hot plate

zinc plated

safety device

adjustable bottom bracket

the raw material hot plate

zinc plating

spring safety device ,2" and 3" safety device

once the cable is broken ,this devoice can keep the hurt away from the door falling

4.aluminum alloy rope pulley

Equipment: CNC stamping/punching machine, CNC bending machine, CNC cutting

machine, 5~250 tons punching machines, welding machine, polish machines...

Processed material: stainless steel: copper, carbon steel

Surface treatment: Hot galvanized, polishing

Making process:Stamping, deep drawing,bending, punching, laser cutting,threading,

welding, tapping, riveting, grinding

5.air bag system

It is a safety device. When the door is down to hit something, it will up automatically.

Operation pressure:<3mbar

Battery:CR2032*2

Battery lifetime>1 year

Emission frequency: 315MHZ

Emission power:<10mW

Receiver power source:12V

6.duplex enhanced guide wheel bracket

Determining the right type of sectional door roller for your garage door tracks can be a little confusing, especially when you do not know what you need to look for in a garage door roller. To simplify things, there are two primary things you need to be aware of. First are the actual dimensions of the roller, and second is purpose that you will be using the door for. You can read below about measuring your roller and choosing the right quality of material for your door.

Other Door Accessories,Electronic Door Accessories,Automatic Door Accessories,High Speed Door Radar Detector

Shenzhen Hongfa Automatic Door Co., Ltd. , https://www.hfrollershutterdoor.com