re peltier effect heat pumps in article snap paj uk co gec mrc paul johnson writes i was having a look through a couple of components catalogues when i came across a range of peltier effect heat pumps intended for cooling components for those who have not heard of this effect you put a current through one of these devices and it pumps heat from one side to the other reverse the current and you reverse the effect i think a temperature difference can give you an emf as well anyway it struck me that you could make a nice cool hot box for picnics with one of these a power regulator a thermostat and a couple of heat sinks the biggest device can shift w with an efficiency of which ain t bad although it would flatten my car battery in about half an hour so called cool hot boxes have been advetised for several years i recall damark advertising them in a recent catalog problem with the units is they do a sh y job of keeping food cold warm the peliter devices used just don t seem to have enough punch to keep up if you want something hot you need to heat it up before you put it in the box and end up hours later with food thats only moderately warm same goes for cold items unfortunately the catalogue didn t list anything more than the basic specs as a heat pump i imagine that you would get a back emf as the temperature gradient across the device increases if so presumably its power decreases as the back emf increases until eventually we have a steady state with no current being consumed assuming no leakage if so then the final temperature difference between the two sides could be set by the supply voltage and nothing more although that would be a lousy way to control it what i would like to know is are the above guesses correct what is the open circuit thermal resistance of a typical device i just want to be sure that my coolbox is not going to get warm too fast when i unplug it you de probably be better off getting a good coleman tm cooler and stocking up on blue ice blocks how does a peltier effect heat pump actually work it looks like magic why don t they use these things in domestic fridges freezers same as above not enough punch in them to keep get things cold hot thanks in advance paul paul johnson paj gec mrc co uk tel ext these ideas and others like them can be had gec marconi research is not for each from any reputable idealist responsible for my opinions mike behnke senior tech advisor quid est illuidin aqua fermi nat accel lab equipment suuport batavia il computing div pistrix pistrix behnke fnalf fnal gov my opinions are my own not of the lab so if you don t like them call uwh iner
