Energy transfer water > air in a greenhouse

  • Context: High School 
  • Thread starter Thread starter SpitfireIX
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around calculating energy transfer in a greenhouse setting, specifically focusing on warming air using water at a higher temperature. Participants explore the necessary formulas for energy calculations related to water and air, as well as the complexities of heat transfer through greenhouse materials.

Discussion Character

  • Homework-related
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant seeks guidance on calculating the energy required to raise the temperature of 100 kg of water and 10 cubic metres of air by 1°C.
  • Another participant mentions the need for specific heat capacities of air and water, as well as the importance of density for mass calculations.
  • A suggestion is made to consult greenhouse manufacturers for technical information that could simplify the problem.
  • Further inquiries are raised about the specifics of the tank and greenhouse conditions, including material composition, temperature differences, and whether a heater is present.
  • It is noted that the basic formula for energy calculations involves specific heat capacity, mass, and temperature change, but the complexity of heat transfer is emphasized.

Areas of Agreement / Disagreement

Participants generally agree on the need for specific heat capacities and the formula for energy calculations, but there is no consensus on the best approach to solve the heat transfer problem, indicating multiple competing views and unresolved complexities.

Contextual Notes

Limitations include missing assumptions about the greenhouse's construction, the specifics of the heating method, and the outdoor and indoor temperature conditions. The discussion highlights the analytical challenges in determining heat transfer accurately.

SpitfireIX
Messages
2
Reaction score
1
How did you find PF?: google

New here. As someone who stopped studying physics and mathematics many decades ago at the age of 16, I don't have much recollection of what I studied. I would appreciate any guidance offered on how to calculate a couple of things, please.

This problem relates to warming air in a greenhouse in winter using water at a higher temperature than the air in the greenhouse

Given:

100 kg of water in a container (tank etc)
10 cubic metres of air in a greenhouse

What formula is used to calculate the energy required to raise the temperature of 100 kg of water by 1C?

What formula is used to calculate the energy required to raise the temperature of 10 cubic metres of air by 1C?

Any advice on how to calculate energy transfer from the air in the greenhouse to the air at a lower temperature outside via its glass panels would be welcome.

Thanks for any answer.
 
Last edited:
  • Like
Likes   Reactions: TensorCalculus
Science news on Phys.org
You need the specific heat capacity of air and water. And also to calculate the mass of something based on its volume you need its density.
 
Last edited:
  • Like
Likes   Reactions: TensorCalculus
Thanks for your reply.
 
:welcome:!
If you're still struggling (though PeroK has given you some very good guidance), do post this question (and any other questions you may have) here. Just make sure to show you attempted it first as well :)
 
SpitfireIX said:
Any advice on how to calculate energy transfer from the air in the greenhouse to the air at a lower temperature outside via its glass panels would be welcome.
This can be a rather complicated problem to work out from first principles. I would start by looking for technical info from greenhouse manufacturers. They would have worked out the details using appropriate assumptions or simplifications, or even using test data from real greenhouses.
 
  • Like
Likes   Reactions: jbriggs444
SpitfireIX said:
100 kg of water in a container (tank etc)
10 cubic metres of air in a greenhouse
Can you please provide more information:
  • What is the tank made of?
  • Is the tank open or closed?
  • What else is the tank for (why have/use a tank?)?
  • How is the water being heated?
  • What is the outdoor air temperature and indoor temperature?
  • What is the greenhouse made of ?

SpitfireIX said:
What formula is used to calculate the energy required to raise the temperature of 100 kg of water by 1C?

What formula is used to calculate the energy required to raise the temperature of 10 cubic metres of air by 1C?
The answer to both is the specific heat capacity times mass times temperature change. But that's not actually what this problem is about. This is a heat transfer problem, and as said it may be very difficult to determine analytically. But maybe there's a shortcut: Does the greenhouse currently have a heater?
 
  • Like
Likes   Reactions: gmax137

Similar threads

  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
Replies
4
Views
601
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 25 ·
Replies
25
Views
6K
  • · Replies 16 ·
Replies
16
Views
7K