The latent heat of vaporization of water at 212 degrees Fahrenheit at atmospheric pressure involving only vaporization and no saturation is 970 BTU/lb, so to evaporate 15 lbs of water we need 970 x 15 = 14550 BTU's
25
100 BTU if it's Fahrenheit
If you're in Celsius, 13459.5 Btu's. If you're in Fahrenheit, 12632.5 Btu's.
160 btu's. It takes 1 btu (British Thermal Unit) to change the temperature of 1lb of water 1°. This is referred to as sensible heat. This 1 to 1 ratio does not hold true when changing the state of that water to ice or to steam. Changing the state 1lb of water at 212° to 1lb of steam at 212° you must add 970 btu's and to change 1lb of water at 32° into 1lb of ice at 32° you must add 144 btu's. This is referred to as latent heat.
144
25
6,520 Btus
There are no BTUs in an office water-cooler. But you can calculate how many BTUs are removed by the cooler. One BTU or British Thermal Unit is the amount of heat energy required to raise the temperature of one pound of water one degree Fahrenheit. There for when you remove one BTU you are lowering one pound of water one degree Fahrenheit. So if you know how many pounds of water you have and the temperature of the water you start with and the temperature of the water comming out of the cooler you can calculate how many BTUs the cooling unit of the water cooler has removed. BTU=Temp1 - Temp 2 X LB water
1)This is a 5 part question. The first is realizing that 20F to 32F uses .5BTU per pound per degree. That means it takes 32-20=12*.5=6BTUs to get the ice to 32F. 2)Then you need to know the Latent Heat of Fusion for Ice which is 144BTUs (given). Lets assumes the ice changes from ice to water instantaneously at 32F. 3)Next we calculate the BTUs from 32F to 212F. Which is 1BTU per pound per degree F. 212-32=180 so it take 180BTUS. 4)Next we have to use the Latent Heat of Vaporization of water which will say instantaneously converts water to vapor. This takes 970BTUS (given). 5)Then we calculate the BTUS from 212F to 220F. Which is .5BTUs per pound per degree F which is 220-212=8*.5=4BTUs...... Finally add up all the BTUs and you get 6+144+180+970+4=1304BTUs.
Near to 400 pounds.One pound of steam requires the input of 1080 btus of heat added to 32oF water at atmospheric pressure. One ton or 2000 pounds requires the input of 2.16 million btus, and a boiler with 80% efficiency (common value) will need 2.7 million btus of heat from the combustion of the wood. Assuming the wood has a btu heat content of 6500 btu/lb (commonly most woods are 6000 to 7000 btu/lb) then about 415 pounds of wood are required to produce 1 ton of steam. In practice only 375 pounds of wood are needed to maintain a steady output of one ton of steam in a boiler, as the water when reintroduced into the boiler is very close to the steaming temperature and doesn't need to be heated from 32oF.
100 BTU if it's Fahrenheit
There are 1078.9 BTUs.
2250
If you're in Celsius, 13459.5 Btu's. If you're in Fahrenheit, 12632.5 Btu's.
Heat. Ice, solid water, at 32 degrees F needs 144 btus of heat per pound to liquify completely. Water at 212F needs 970.3 btus per pound to evaporate completely into dry steam. Water vapor (visible steam), in air, {say from a pot} is actually about 3 to 10% dry steam and only required about 28 to 100 btus per pound to vaporize and become airborne, This is an odd characteristic of water, that varying proportions of dry steam will carry large amounts of liquid water along with it as it evaporates (Wet Steam).Water can exist in all three states at the same time, in the same general vicinity. Ice floats on liquid water and the air around it will also contain some amount of water vapor (humidity).
The specific heat of water is 1 BTU per pound per degree Fahrenheit. There are 8.3378 lbs/gallon at 60 degrees, which equals 3251.742 pounds of water. The number of BTUs to raise it 188 degrees is then 611,327.496 BTUs.
BTUs to Evaporate One Pound of WaterQuick Answer: Somewhere around 1000BTU/lb Long answer: It depends on the temperature of the water you start with. Before you can evaporate the water, you must heat it to it's boiling point. The warmer the water you start with the fewer BTUs will be needed to heat the water to its boiling point. Keep in mind the BTUs require to raise the water to its boiling point are very few compared to the BTUs required to change the water from a liquid to a gas.One pound of steam contains 1150 BTUs. This is the energy you need to put into the water for it to evaporate if you start with water at 32F. If you start with water at 100F the water already has 70 BTU/lb so the BTUs required to evaporate the water when you start at 100F is 1150-70 = 1080 BTU and so on.You can get all this information in a steam table which can be found easily by searching the web.