How many btu's would be required to raise 45 pounds of water 18 degrees Fahrenheit?

Answer 1

A british thermal unit (btu) is the amount of heat required to raise 1 pound of water 1 degree fahrenheit. How many btu's would be required to raise 45 pounds of water 18 degrees fahrenheit?

Solution 44430

Amount of heat

= {(1 btu) / [(1 lb)(1 F)]} * (45 lb) * (18 F)

= 810 btu

Answer 2

202.3 btu

According to Keenan and Keyes, 1 lb of water at 100psia requires 298.4 btu to raise it's temperature from 32 degrees to 327 degrees F. that is 1.0115 btu per pound. So 2 lbs of water would require 202.3 btu to raise it's temperature at 100 psia 100 degrees F. (from between 32F-227F to a higher temperature between 132F-327F)

At 100psia any addition of heat to water at 327F will result in the generation of steam and no increase in temperature.

**Note: closed feed water heaters (heat exchangers) work on this principle of cooler water under pressure being heated to boiler temperatures to avoid thermal shock to the boiler, for a practical application. It is generally assumed that one pound of water requires 1 btu of heat to raise it's temperature 1 degree despite it's pressure. This assumption is only slightly incorrect at low pressures (less than 600 psia), but more flawed at higher pressures, as evidenced by heat-entropy tables showing a larger increase in heat required as the pressures approach critical pressures. (water at 3206 psia requires 902.7 btu to raise it's temperature 671.4 degrees or 1.3445 btu per pound [at this pressure water converts directly to steam with no latent heat required]).

Answer 3

To calculate the amount of energy required to raise the temperature of water, you can use this formula: Heat energy (BTUs) = weight of water (lbs) x temperature change (°F) x specific heat capacity of water. For water, the specific heat capacity is 1 BTU/lb°F. Using this formula, the amount of energy required to raise 45 pounds of water by 18 degrees Fahrenheit would be: 45 lbs x 18°F x 1 BTU/lb°F = 810 BTUs.

Answer 4

45 pounds x 18* F = 810 BTU’s

Answer 5

810