How many Wh of heat does each Hot Hands packet offer?

How many Wh of heat does each Hot Hands packet offer?
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answer:I do not have the absolute scientific answer for you but I do have a subjective one that might help others answer your question. First I commend you for asking the question in the form of Watt-hours for total heat , and power for max output. That is the correct way to do it and will enable you to compare the output with other devices and systems. I have used similar chemical heaters in the past and they “feel” like a 2 watts battery heater for the first hours or two (call it 1.5 hours) and then taper off to a watt for the remaining 4. That gives me the purely subjective answer of 7 Whr. How does that compare with other things? A typical AA battery has a capacity of 4 Whr so you can figure a chemical heater is about 2 energizer alkaline batteries. Total cost about $0.80 What would electricity cost for that heat? In my area electricity cost 12 cents per kWhr . 7 Whr at $ 0.12 / 1000 Whr = $0.00084 = ~ 0.1 cents Batteries and chemical heaters are very expensive when compared with electricity.
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Description : n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture  is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In  each batch about 120 ... dryer and the dryer efficiency  is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.

Last Answer : Given that   Qty of material dried per batch - 120 Kgs  Moisture at inlet - 60% a. The quantity of moisture removed per batch.  Water quantity in a wet batch - 120 x 0.6 = 72 Kgs.  Quantity of bone dry ... - 48/0.95 = 50.5 Kgs.  Equivalent water in a dry batch - 50.5 - 48 = 2.5 Kgs.

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