Monday 16 August 2010

Wet bulb temperatures Gambia

The wet bulb temperature is as cool as the Desert Fridge could possibly get. Since it is currently being used in Gambia, I have plotted the wet bulb temperature and normal (dry bulb) temperature for the average day time climatic conditions in Banjul (Gambia).


The “ambient” values were obtained from looking up data for the max average temperature found here.
The wet bulb temperature was calculated from the respective ambient temperatures and relative humanities (again from here - lookup “pm”) using this applet (setting pressure to 760mmHg = 1atm). This could also be found by using a psychometric chart but I couldn't be bothered.

Overlaid are the upper limit for the optimum cold storage temperatures for fruit and vegetables which are commonly grown and consumed (or wasted) in Gambia.

This may explain the excellent results recorded from the experiment conducted at the University of The Gambia in January 2009 where it was shown that the shelf life of tomatoes could be significantly extended in the Desert Fridge (see report here).

However it also reveal that the Desert Fridge would not be adequate for storage of most fuit and vegetables throughout the year. Conveniently though, the greatest demand for storage in Gambia we have observed to be is in the dry season (oct/nov to may/jun) and that is of tomatoes.

Nevertheless this means we need to develop an improved solution to meed these requirements.

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