Is there a common measurement term for joules/volume/°C?

  • Thread starter Thread starter some bloke
  • Start date Start date
  • Tags Tags
    Measurement Term
AI Thread Summary
The discussion centers on finding a common measurement term for thermal energy storage that combines joules, volume, and temperature. The focus is on converting specific heat capacity from a mass-based to a volume-based measurement to maximize energy storage in a thermal store. Hydrogen is noted for its high specific heat capacity, but water is favored for its practicality, cost-effectiveness, and efficiency in heat exchange. The concept of volumetric heat capacity is introduced as a relevant measurement term, combining density and specific heat capacity. Overall, the conversation emphasizes that the highest specific heat capacity alone does not guarantee maximum usable energy for practical applications.
some bloke
Messages
283
Reaction score
99
TL;DR Summary
I am looking to find the highest thermal energy density per volume, for a mass heater project.
I need to work out the maximum thermal energy which can be stored within an area, and to do this I need to convert the specific heat capacity (which measures by mass) to measure instead by volume. Is there a common measurement term I can search for (in the same way as I might search "specific heat capacity of _X_") that I can look for?

Currently I'm finding that hydrogen has the highest SHC, but I feel it might be difficult to make something out of it!

The goal is to be able to store as much energy as possible in a mass, and then for it to reduce as little as possible whilst it heats the water I run through it! I know that it will take longer to heat a mass with more SHC, but that's not an issue!

Also, Am I correct that I need the highest specific heat capacity to store the maximum energy for this project?
 
Engineering news on Phys.org
Can you use a phase change? There are eutectic salts that can be tuned to the transition temperature you want. They store a lot of energy.
Otherwise water has a very high heat capacity.
 
  • Like
Likes sophiecentaur
What you are talking about is called a thermal store. Water is generally used because (i) it has a high specific heat capacity (ii) it is easy to get heat into the store (just pump in hot water) (iii) heat exchangers for getting heat out of the store work best with fluids (iii) it is cheap. Even if you find something that is better at a combination of (i), (ii) and (iii), water will almost always win hands down on (iii) (the exception being if you want a temperature out that is near boiling).

some bloke said:
Also, Am I correct that I need the highest specific heat capacity to store the maximum energy for this project?
No, you can store the maximum energy with the highest heat capacity (i.e. specific heat capacity x mass). However what you need is the maximum usable energy: if you want a mug of boiling water, 1MJ of heat energy at 50°C is not a lot of use to you.

So design parameters for a thermal store are more than just 'store as much thermal energy as possible'.
 
Last edited:
some bloke said:
Is there a common measurement term I can search for

Sounds like you are defining volumetric heat capacity.
 
onatirec said:
Sounds like you are defining volumetric heat capacity.
@onatirec beat me to it.

##density~ \frac {lbm} {ft^3} * sp~ heat~ \frac{Btu} {lbm~-~F} = \frac {Btu} {ft^3 ~-~F}##

Sorry for the units, a lifetime habit
 
Thread 'What type of toilet do I have?'
I was enrolled in an online plumbing course at Stratford University. My plumbing textbook lists four types of residential toilets: 1# upflush toilets 2# pressure assisted toilets 3# gravity-fed, rim jet toilets and 4# gravity-fed, siphon-jet toilets. I know my toilet is not an upflush toilet because my toilet is not below the sewage line, and my toilet does not have a grinder and a pump next to it to propel waste upwards. I am about 99% sure that my toilet is not a pressure assisted...
After over 25 years of engineering, designing and analyzing bolted joints, I just learned this little fact. According to ASME B1.2, Gages and Gaging for Unified Inch Screw Threads: "The no-go gage should not pass over more than three complete turns when inserted into the internal thread of the product. " 3 turns seems like way to much. I have some really critical nuts that are of standard geometry (5/8"-11 UNC 3B) and have about 4.5 threads when you account for the chamfers on either...
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'
Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
Back
Top