Effect of Pressure on Heating (not boiling) water

In summary, applying pressure to water in a closed system increases the boiling point. In the experiment described, the system is at atmospheric pressure and reaches a temperature of 65 degrees C, while at 100 PSI, the temperature only reaches 47 degrees C. This could be due to differences in flow rates and a small change in heat capacity due to changes in density at higher pressure. Further research and experimentation may be necessary to fully understand the effects of pressure on water temperature.
  • #1
TandemDrip
1
0
I understand that if I apply pressure to water in a closed system, the boiling point increases. So at atmospheric pressure, it boils at 100 degrees C and at 100 PSI, this number increases to 164 degrees C. In my experiment, I'm using the sun to heat the water as it runs through a solar water heater on the roof. What I don't understand is why if I have the system at atmospheric pressure, it gets hotter than is I pressurize the circuit at 100 PSI. For example, at atmospheric pressure, I can get 65 degrees from my collector, but if I prime the circuit to mains pressure of 100 PSI, I struggle to get 47 degrees C. Why ? Can someone please explain this and provide a reference for me to research this more.
 
Science news on Phys.org
  • #2
TandemDrip said:
I understand that if I apply pressure to water in a closed system, the boiling point increases. So at atmospheric pressure, it boils at 100 degrees C and at 100 PSI, this number increases to 164 degrees C. In my experiment, I'm using the sun to heat the water as it runs through a solar water heater on the roof. What I don't understand is why if I have the system at atmospheric pressure, it gets hotter than is I pressurize the circuit at 100 PSI. For example, at atmospheric pressure, I can get 65 degrees from my collector, but if I prime the circuit to mains pressure of 100 PSI, I struggle to get 47 degrees C. Why ? Can someone please explain this and provide a reference for me to research this more.

Are you sure it's not just a question of flow rates? Unless you are regulating the flow somehow, the rate will be much faster at 100 psi, and so there will be less time for the water to absorb heat as it runs through the solar heater. There could also be a small increase in the heat capacity due to changes in the density at the higher pressure, but since water isn't very compressible, I would think that it is basically negligible.
 

1. How does pressure affect the boiling point of water?

The boiling point of water is directly proportional to the pressure applied. As pressure increases, the boiling point also increases. This is because at higher pressures, the water molecules are under more force and it takes more energy to break the bonds between them and turn them into vapor. Therefore, the boiling point of water increases as pressure increases.

2. Does pressure also affect the heating of water?

Yes, pressure also affects the heating of water. As pressure increases, the water molecules are more tightly packed together and it takes more energy to increase their temperature. This means that water will take longer to heat up under higher pressures compared to lower pressures.

3. How does pressure affect the rate of heating water?

The rate of heating water is affected by pressure in two ways. Firstly, as mentioned before, higher pressures require more energy to increase the temperature of water. Therefore, the rate of heating will be slower under higher pressures. Secondly, at higher pressures, the boiling point of water is also higher. This means that the water will not start to boil and evaporate until it reaches a higher temperature, causing a delay in the heating process.

4. Can pressure affect the taste of heated water?

Yes, pressure can affect the taste of heated water. When water is heated under high pressure, it may absorb more minerals and gases from the surrounding environment, which can alter its taste. Additionally, water that has been heated under high pressure may taste flatter compared to water that has been heated under normal atmospheric pressure.

5. Is it safe to heat water under high pressure?

Heating water under high pressure can be dangerous and should only be done with proper safety precautions in place. The high pressure can cause water to rapidly boil and potentially cause explosions. It is important to use appropriate equipment and follow safety guidelines when heating water under high pressure to prevent any accidents.

Similar threads

I Trying to wrap my head around gas turbine thermodynamics
    • Thermodynamics
Replies
5
Views
641
Vapor pressure -- How does water still boil at 100°C in an open pot?
    • Chemistry
2
Replies
35
Views
3K
I Measuring Steam Condensate from my Steam Cleaner
    • Thermodynamics
Replies
8
Views
1K
Help understanding "Heat capacity"
    • Thermodynamics
Replies
28
Views
1K
Heating up water versus water with an iron brick
    • Thermodynamics
Replies
7
Views
1K
B Heat Pumps And The Peltier Effect
    • Thermodynamics
Replies
6
Views
1K
Freezing Engine and Specific Heats
    • Thermodynamics
Replies
1
Views
642
How does evaporation generate cooling? Swamp coolers edition
    • Thermodynamics
Replies
32
Views
2K
Can passive heat collection be used to heat water to very high temperatures?
    • Mechanical Engineering
Replies
8
Views
1K
A What is the heat capacity of water in meta-stable equilibrium?
    • Classical Physics
Replies
2
Views
432

Hot Threads

Recent Insights

Back
Top