Flow increase requirements when Glyocol is added

[Longhair]

As we know, as the % of glycol is added to a system, more flow is required for the same amount of btu's. I have a small program that is capable of this, but it is not windows friendly and I have come across a situation that makes me suspect the program has a flaw. I use Excel extensively for estimateing and for shop dwgs and valve sizing etc. Does someone have a precise formula for the required increase in flow for varying glycol concentrations. To go one further, does someone have a formula that will allow you to enter the required BTU's, Water Temp in, Water Temp out, and glycol concentration thus calculate the required GPM of fluid?

 

[pardal]

The relation is about the especific heat from water to water+glicol.
Maybe you need to search about this value.

Heat = massflow x Specific heat x (T in - T out)




Pardal

 

[VSSriram]

Flow in GPM = Cap in TR x 12000 / (500 (Sp heat) x Delta T)

This is for water. The only variable between water and glycol would be the factor of 500 - i.e. Sp heat. If you were to add glycol, this factor would be change to less than 500, say 425 or 435 depending on the concentration of glycol that you are adding.

There must be a table giving these values. I can't lay my hands on it immediately. But, can find out, time permitting.

Sriram

 

[Cooky]

The best source for this information is a manufacturer or supplier of water treatment products. There are many variations on the standard glycol product.

I have a chart that shows changes in pressure drop, flow rate and capacity, against the % of ethylene glycol. If you want a copy, post your fax number (including the international dialling code when dialling from the UK).