1,Chilled water pump: a device that drives the circulation of water in a chilled water loop. The end of an air conditioning room (such as a fan coil unit, an air handling unit, etc.) requires cold water from the chiller. However, refrigerated water does not flow naturally due to the limitation of resistance, which requires the pump to drive the cooling water for circulation to achieve the purpose of heat transfer.
2,The cooling water pump in cooling water loop drive water device for circulating cooling water. As we know, take part in the refrigerant heat chiller, cooling tower and flows into the heat release. The cooling water pump is responsible for driving the cooling water circulating in the cooling tower and the unit closed loop shape. With the chilled water pump.
3,Feeding water pump: air conditioning water supply device, responsible for the treatment of soft water into the system.
The commonly used pumps are horizontal centrifugal pumps and vertical centrifugal pumps, which can be used in chilled water systems, cooling water systems and supplementary water systems. For the machine room area small place may consider using the vertical centrifugal pump.
When the pump runs in parallel, the flow rate is attenuated. When the number of parallel lines is over 3, the attenuation is particularly severe.
A. when a number of pumps are selected, the attenuation of the flow is considered, and the allowance for 5% to 10% is generally added.
It is not suitable for
B. pumps in parallel to more than 3 units, that is, more than three units should not be selected for the selection of the main engine.
C. Cold and hot water circulating pumps should be installed separately for large and medium projects.
In general, the number of chilled water pumps and cooling pumps should correspond to the refrigeration mainframe one by one, and one standby should be considered. The feedwater pumps are generally selected according to the principle of one use and one preparation to ensure the reliable replenishment of the system.
Calculation of pump flow
(1) the formula for calculating the flow rate of the frozen water pump and the cooling water pump:
L（m3/h）=Q(Kw)×(1.15~1.2)/(5℃×1.163)
Medium: refrigerating capacity of Q– refrigerating mainframe, Kw.
L– refrigerated cooling water pump flow, m3/h.
2) flow rate of the recharge pump:
The normal recharge water quantity is 1 / 2 of the circulating water quantity of the system, but when selecting the recharge pump, the flow rate of the recharge pump should be satisfied with the normal replenishment quantity of the water system mentioned above. It is also necessary to consider the increase in the amount of recharge water in the event of an accident. Therefore, the flow rate of the recharge pump is usually not less than 4 times of the normal replenishment volume, and the effective volume of the recharge tank can be considered according to the normal recharge volume of 1 ~ 1. 5 h.
Determination of pump head
Composition of chilled water pump heads:
Evaporator Water Resistance of Refrigeration Unit: 5m H 2O generally (see product sample for details)
End equipment (air treatment unit, fan coil unit, etc.) water resistance of the surface cooler or evaporator: generally 5m H 2O; (see product sample for specific values)
The resistance of backwater filter and two-way regulating valve is generally 3 ~ 5mH _ 2O;
Water resistance of water separator: 3 m H 2O;
The loss of resistance and local resistance along the pipe path of refrigeration system is generally 710mH2O;
To sum up, the head of the chilled water pump is 265mH2O, usually 32mH2O. Note: the calculation of the head should be based on the specific conditions of the refrigeration system, not to copy the empirical value!
(2) the composition of the head of the cooling water pump:
Water resistance of condenser in refrigerating unit: generally 5~7mH2O; (specific value can be seen as a sample of products)
The sprinkler pressure of the cooling tower is generally 2~3mH2O;
The height difference between the cooling tower (open cooling tower) and the nozzle to the nozzle: generally 2~3mH2O;
The resistance of the backwater filter, the two pass regulating valve, and so on, is generally 3~5mH2O;
The resistance and local resistance loss of the water pipe road in the refrigeration system are generally 5~8mH2O;
To sum up, the cooling water pump head is 17~26mH2O, generally 21~25mH2O.
Water pump head: the lift is the rich lift with constant pressure point and the highest point distance from the water suction end and outlet end of the pump.
Method for calculating resistance of water pipes:
Along the resistance of water in the pipeline:
Hf=Rl
In the middle of the equation, the resistance of the water pipe along the path is Pa.
R- drag per unit length along the path, also known as the specific friction resistance Pa / m;
L- the length of the straight section of the water pipe.
When a steel pipe or galvanized pipe is adopted in the cold water pipe , the specific friction resistance R is generally 100 – 400Pa / m , and the most commonly used is 250Pa / m . Specific friction resistance is an amount related to the pipe diameter , the water flow velocity and the flow rate , and can be obtained by the following specific friction resistance calculation diagram . ( 2 ) Local resistance : When water flow encounters elbow , tee and other accessories , the calculation formula of local resistance due to friction and eddy current consumption is : Hd = zeta × ( ρ × V2 / 2 ) In the formula , the local resistance coefficient , V _ water flow rate , m / s . 3 . Total water pipe resistance The total resistance H ( Pa ) of the water flow consists of the path resistance Hf and the local resistance Hd , that is , H = Hf + Hd .
2,The cooling water pump in cooling water loop drive water device for circulating cooling water. As we know, take part in the refrigerant heat chiller, cooling tower and flows into the heat release. The cooling water pump is responsible for driving the cooling water circulating in the cooling tower and the unit closed loop shape. With the chilled water pump.
3,Feeding water pump: air conditioning water supply device, responsible for the treatment of soft water into the system.
The commonly used pumps are horizontal centrifugal pumps and vertical centrifugal pumps, which can be used in chilled water systems, cooling water systems and supplementary water systems. For the machine room area small place may consider using the vertical centrifugal pump.
When the pump runs in parallel, the flow rate is attenuated. When the number of parallel lines is over 3, the attenuation is particularly severe.
A. when a number of pumps are selected, the attenuation of the flow is considered, and the allowance for 5% to 10% is generally added.
It is not suitable for
B. pumps in parallel to more than 3 units, that is, more than three units should not be selected for the selection of the main engine.
C. Cold and hot water circulating pumps should be installed separately for large and medium projects.
In general, the number of chilled water pumps and cooling pumps should correspond to the refrigeration mainframe one by one, and one standby should be considered. The feedwater pumps are generally selected according to the principle of one use and one preparation to ensure the reliable replenishment of the system.
Calculation of pump flow
(1) the formula for calculating the flow rate of the frozen water pump and the cooling water pump:
L（m3/h）=Q(Kw)×(1.15~1.2)/(5℃×1.163)
Medium: refrigerating capacity of Q– refrigerating mainframe, Kw.
L– refrigerated cooling water pump flow, m3/h.
2) flow rate of the recharge pump:
The normal recharge water quantity is 1 / 2 of the circulating water quantity of the system, but when selecting the recharge pump, the flow rate of the recharge pump should be satisfied with the normal replenishment quantity of the water system mentioned above. It is also necessary to consider the increase in the amount of recharge water in the event of an accident. Therefore, the flow rate of the recharge pump is usually not less than 4 times of the normal replenishment volume, and the effective volume of the recharge tank can be considered according to the normal recharge volume of 1 ~ 1. 5 h.
Determination of pump head
Composition of chilled water pump heads:
Evaporator Water Resistance of Refrigeration Unit: 5m H 2O generally (see product sample for details)
End equipment (air treatment unit, fan coil unit, etc.) water resistance of the surface cooler or evaporator: generally 5m H 2O; (see product sample for specific values)
The resistance of backwater filter and two-way regulating valve is generally 3 ~ 5mH _ 2O;
Water resistance of water separator: 3 m H 2O;
The loss of resistance and local resistance along the pipe path of refrigeration system is generally 710mH2O;
To sum up, the head of the chilled water pump is 265mH2O, usually 32mH2O. Note: the calculation of the head should be based on the specific conditions of the refrigeration system, not to copy the empirical value!
(2) the composition of the head of the cooling water pump:
Water resistance of condenser in refrigerating unit: generally 5~7mH2O; (specific value can be seen as a sample of products)
The sprinkler pressure of the cooling tower is generally 2~3mH2O;
The height difference between the cooling tower (open cooling tower) and the nozzle to the nozzle: generally 2~3mH2O;
The resistance of the backwater filter, the two pass regulating valve, and so on, is generally 3~5mH2O;
The resistance and local resistance loss of the water pipe road in the refrigeration system are generally 5~8mH2O;
To sum up, the cooling water pump head is 17~26mH2O, generally 21~25mH2O.
Water pump head: the lift is the rich lift with constant pressure point and the highest point distance from the water suction end and outlet end of the pump.
Method for calculating resistance of water pipes:
Along the resistance of water in the pipeline:
Hf=Rl
In the middle of the equation, the resistance of the water pipe along the path is Pa.
R- drag per unit length along the path, also known as the specific friction resistance Pa / m;
L- the length of the straight section of the water pipe.
When a steel pipe or galvanized pipe is adopted in the cold water pipe , the specific friction resistance R is generally 100 – 400Pa / m , and the most commonly used is 250Pa / m . Specific friction resistance is an amount related to the pipe diameter , the water flow velocity and the flow rate , and can be obtained by the following specific friction resistance calculation diagram . ( 2 ) Local resistance : When water flow encounters elbow , tee and other accessories , the calculation formula of local resistance due to friction and eddy current consumption is : Hd = zeta × ( ρ × V2 / 2 ) In the formula , the local resistance coefficient , V _ water flow rate , m / s . 3 . Total water pipe resistance The total resistance H ( Pa ) of the water flow consists of the path resistance Hf and the local resistance Hd , that is , H = Hf + Hd .
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Gelaili pump industry co.,ltd supplies you competitive price and high quality products.
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