• m3/h ( kcal/h btu/h ) / . .
, Darcy-Weisbach : hf = f * ( L / D) * (V2 / 2 * g).
Km (Km) .
f colebrook , Moody.

:

1. (, cp) 90oC , 1bar .
1. (, cp) 5oC , 1bar .
3. .

This Little program calculates the necessary water flow (in m3/h) to transfer heating or cooling energy (in kcal/h and btu/h respectively) for a given temperature difference.  You may also calculate (if you enter the flow rate) the heat/cool transfer capacity of the given flow rate (for the given temperature difference of course).

Then , the program will calculate velocity , and by clicking the calculate button the energy loss in the pipe ,using the popular Darcy-Weisbach equation :
hf = f * ( L / D) * (V2 / 2 * g).

In order to calculate the minor losses (fittings) you must add the corresponding Km values from the table below , and enter them in the Km textbox  of applet.

 Fitting Km Globe valve, fully open 10.00 Angle valve, fully open 2.00 Gate valve, fully open 0.15 Gate valve, 1/2 closed 2.10 Swing check valve , flow 2.00 Elbow 90o - flanged 0.30 Elbow 90o - threaded 1.50 Long radius 90, flanged 0.20 Long radius 90, threaded 0.70 Elbow 45, threaded 0.40 Tee , Line flow, flanged 0.20 Tee , Line flow, threaded 0.90 Tee , Branch flow, flanged 1.00 Tee , Branch flow, threaded 2.00 Piping Entry & Exit 1.00

The value of  friction factor f is calculated using the colebrook equation , and can be checked using the Moody diagram.

Before you use the program , you should read the following:

1. The water properties (viscosity , density and cp) for heating are calculated for 90oC temperature (1bar).
2. The water properties (viscosity , density and cp) for cooling are calculated for 5oC temperature (1bar).
3. Generally the program provides a very good approximation for different temperatures or pressure NEAR these values.

Below is given a general diagram to explain the use of the program.

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