subject: Deep well pump frequency of the groundwater source heat pump - water source heat pump, air conditioning - heat pump industry [print this page] Deep well pump frequency of the groundwater source heat pump - water source heat pump, air conditioning - heat pump industry
>> Abstract: Currently, ground water source heat pump air conditioning system, often a deep well of water supply to meet the required two or more of water heat pump unit. However, in actual operation found that most of the time heat pump part load operation, while the deep well pump has been running at full capacity, resulting in a significant increase in electricity and water charges. For this problem, this paper actually works, for example, frequency conversion technology using deep well pump variable flow water pump on the well water that meets the requirements, but also save energy and well water quantity, introduced the deep well pump variable frequency control method and principle, frequency range OK, and operation under the deep well pump test results, analysis of the energy saving effect and the economy.
Keywords: Frequency range of deep well water supply energy saving power consumption
1 Foreword Recent years, the frequency control technology, with its significant energy savings and reliable way to control air-conditioning systems are used mostly in pumps and fans, and its technology is more mature, but in the ground water source heat pump system, deep well pump water application, currently it is very unusual, but quite necessary. Shenyang area groundwater heat pump application pilot survey found that ground water source heat pump system, when the heat pump capacity is not a deep well of water supply to meet the required two or more of water heat pump unit. Found in actual operation, heat pump part load most of the time to run, but deep well pump has been running at full load conditions, resulting in a substantial increase in electricity and water charges. So deep well pump frequency control water supply in groundwater source heat pump system has great energy potential.
2 Project Overview Of this article with concrete projects for the Winter study, project profile as follows:
Floors of a five-story office building of new area, construction area of 11030m2, summer air-conditioning cooling load for the 894kw, winter air conditioning design heat load 1012kw. Office building with two cold sources of groundwater source heat pump, heating conditions: the heating capacity of 515kw, input power 136.02kw, cold water flows 65m3 / h, water volume 88.6m3 / h, a pumps pumping 160m3 / h, Power 37kw. Winter hours: November to 3 months, 24 hours a day to run.
3 deep well pump frequency control water supply control
Deep well pump with temperature control method. As the heat pump in heating conditions, the need to ensure that the evaporator outlet temperature is not excessively low return water pipe located in the deep-well pump temperature sensor, set the temperature tjh. Well water side of the return water temperature is greater than tjh value, the deep well pump controller issued to reduce the current frequency signal frequency converter, frequency converter reduces the input power supply, deep well pump's switch to lower the number, pumps water supply, power and motor shaft input power also decreases, so as to achieve the purpose of energy saving. When the water side of the return water temperature is below tjh value, by frequency adjustment.
4 pump speed adjustment principle Change the pump speed, pump performance can be changed to achieve the purpose of adjusting the operating point. Under similar law, for the same pump at different speed operation, the pump flow, head, shaft power and speed relationship can be expressed as:
Q / Qe = n / ne (1) H / He = (n / ne) 2 (2)
P / Pe = (n / ne) 3 (3)
Type in: ne?? Pump rated speed, r / min; n?? Actual operating conditions of speed, r / min;
Qe?? Pump rated speed of the flow, m3 / h; Q?? Actual operating conditions of flow, m3 / h;
He?? Pump rated speed of the head, m; H?? Actual operating conditions of the head, m;
Pe?? Pump rated speed power, kw; P?? Actual operating conditions of power, kw.
By (1) type and (2), we can get
H1/Q12 = H2/Q22 = k (4)
That H = kQ2 (5) (5) style is the coordinate origin as the vertex of a parabola, the points line with similar condition, known by the similarity law, when the pump speed changes before and after the time when the efficiency of the same pump, so similar conditions also known as the efficiency of the parabolic curve, etc.. Therefore, from the energy point of view, usually changing the pump speed method to change the pump operating point, try to make it in the high efficiency range.
5 to determine pump frequency range
Load changes when the heat pump, deep well pump in the water supply changed also. Deep well pump in the water supply in the (Qmin ~ Qe), and that means deep well pump in the frequency range (nmin ~ ne), shown in Figure 1.
Heat pump minimum flow rate required to 40m3 / h (equipment requirements), that is, the minimum deep well water supply, the minimum speed deep well pump: too:
Nmin = Qmin / Qe ne = 40/160 2900 = 725 r / min Winter heating condition
deep well in the frequency range: 725 r / min to 2900 rev / min.
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