Heat loss due to open doors.

[darrin]

Hi everyone.

I want to know if anyone can help me calculating the heat loss due to an open cold store door.

The average door size is 2.2m(w) X 3.0m(h) and the average room size is 2100m3. The room temp is between -1 and +2 degrees celcius, with an average ambient of +25 degrees C.

The idea is to covert the heat loss to currency, therefore knowing how much money can be saved just by keeping the cold store doors closed.

Any help in this regard will be much appreciated.

[Bhushan Malik]

Hi Darrin,

Did you get any response to your request for info concerning cooling loss due to open doors - I have similar issues on many refrigeration doors - a company called Clark Doors Tel +44(0)1228 522321 use a software and enter all relavant data such as door sizes, opening times frequency of operation, site operating hrs/week, condition of door & seals, the country annual temperature and humidity profile and cost of electricity /kWh.

Their software then calculates the annual savings in currency terms - I am however interested in calculating the losses from first principles - if you have had any response I shall be grateful if you could let me know the method of calculation.

Regards,
Bhushan

[Sridhar1312]

Normally cold rooms are provided with ante room as well as PVC strip doors to prevent cold air loss or to prevent ingression of outside air in to the cold room.
Best way to get the energy loss due to door opening is to measure the energy consumed during the door open situation for the refrigeration system and also measure energy consumption when the door is closed.
Difference in energy is the additional energy required for refrigeration system when the door is kept open.

[Tesla]

If you search Tamm's equation - this will give an estimation of velocity and also professors Cleland of Massey University You will find this formula. Sorry I don't know how to put all the symbols in on my computer and require more data (variables) to give an answer from my calculator, such as density, enthalpys and flow rate (Tamm's). There have been some adjustments made to the formulas to increase accuracy in recent years. The sites I checked want you to pay for the PDF but I'm sure there are free formula somewhere.
As above it can be measured but this takes much more time and money.