Calculate work needed to evaporate water

  • Thread starter Thread starter pikiche
  • Start date Start date
  • Tags Tags
    Water Work
AI Thread Summary
To calculate the work needed to evaporate water from washed clothes in a well-isolated room at 75°F, the energy required can be determined using the formula Q = m h_{fg}, where Q is the energy, m is the mass of water, and h_{fg} is the latent heat of vaporization. Additionally, the sensible heat must be considered, incorporating the specific heat and temperature change with the equation q = m h_{fg} + m c_{p} ΔT. This approach highlights that the energy required for evaporation varies with the initial temperature of the water. The discussion also emphasizes the importance of calculating the energy costs associated with line drying versus using an electric dryer, factoring in the energy needed to maintain the room temperature. Understanding these calculations can help in estimating potential savings from line drying clothes.
pikiche
Messages
2
Reaction score
0
how would you calculate the work needed to evaporate water from washed clothes, if the clothes r in a well isolated room with temperature of 75F
help pleasezzz
 
Engineering news on Phys.org
The energy required is the mass of water multiplied by the laten heat of vaporization:

Q = m h_{fg}

Q = energy required
m = mass of water
h_{fg} = latent heat of vaporization

If you want to estimate how long it will take to evaporate naturally, search for "swimming pool evaporation equation."
 
edgepflow said:
The energy required is the mass of water multiplied by the laten heat of vaporization:

Q = m h_{fg}

Q = energy required
m = mass of water
h_{fg} = latent heat of vaporization

If you want to estimate how long it will take to evaporate naturally, search for "swimming pool evaporation equation."

No, he said it starts off at 75 degrees. Surely that has to be taken into account. I mean, it CAN'T take the same amount of energy to evaporate water at 1 degree above freezing as to do it to water at 1 degree below boiling.
 
phinds said:
No, he said it starts off at 75 degrees. Surely that has to be taken into account. I mean, it CAN'T take the same amount of energy to evaporate water at 1 degree above freezing as to do it to water at 1 degree below boiling.
The sensible heat can be included as follows:

q = m h_{fg} + m c_{p}\DeltaT

cp = specific heat
\DeltaT = temperature change = 212 F - 75F
 
thank you for the reply guys, see what I am trying to do is actually calculate how much money would u save from line drying clothes vs using an electric dryer. knowing that u have an ac/ heater at the houseto keep the temperature at 75. so i was thinking that after calculating the heat to evaporate the water from the clothes wouldn't be the same amount of energy that the ac/heater has to apply to maintain the temperature at 75?
 
Back
Top