I recently was looking at specifications for solar powered vaccine refrigerators in the PIS and PQS specifications. I was trying to do a comparison of the various models and found it difficult.
For each model the data given is for different test conditions. For example, energy use data for True Energy Model PS65i is given for stable run conditions at 43 deg C, 32 deg C, and 27 deg C and also energy use for the cool down test at 43 deg C. No energy use figures are given with ice making. For the Dometic SARL TCW 2000DC 43 deg C energy use is given for stable run conditions with the refrigerator compartment on and freezer turned off and energy consumption for ice making at 43 deg C.
When sizing a solar system the data most commonly needed is energy consumption at 32 deg C with and without ice making.
Another point which could be presented more clearly is which of the compressors is running on two compressor models.
These issues could easily be cleared up; since all the necessary data was generated when the PQS tests were carried out.
Dear Larry,
Thank you for making this very relevant remark. As you say this can be easily rectified as data is available. I am in fact working right now on the format of the datasheets for our new web based database and I certainly will take into account your remark. The advantage of the new system is that the data extracted from the database will be the same for all appliances and therefore avoid inconsistencies. Note that our present policy encourages manufacturers to test their appliances at several ambiant temperatures (43°C, 32°C and 27°C) but requires data from only one of the three temperatures. Data is published with the agreement and as per the request of the manufacturer who bears the responsibility of its validity.
Regards,
Denis Maire, WHO PQS
Larry,
Actually the figure for ice pack freezing for the True Energy PS65i does appear on the PQS sheet - See: E003/016 and check the line : Water-pack freezing: energy.
If you look at the test protocol you'll find that this is the power consumption for the fridge/freezer whilst freezing ice.
I agree that stable running figures should be reported consistently. As stated in the PQS test protocol, the stable running power consumption should be measured with the freezer turned ON. This is the case with the PS65i PQS sheet but not with all PQS sheets as you rightly point out - Presenting further data is optional of course but we should all present a full set of results as required by the PQS testing.
I also agree that 32C is most often used for solar power system however if we are to qualify as a product at the highest temperature (Hot Zone) then we must of course focus on results from our tests at 43C - Perhaps the PQS tests should move to a requirement for testing at 32C with optional additional tests to prove the appliances performance under other conditions?
Ian Tansley - CTO True Energy
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