Heat transfer for a cold water dispensor.

[kgmilano]

good afternoon


i have a project to build a water dispenser. I'm strugling with heat transfer equations since it's cold that is being transfered. do i use the standard heat transfer equations even for cold? which equations do i use. water will be inside a 100x100x150 (1.5 litres) casing made out of aluminium.

thanks

 

[Mech_Engineer]

Any heat transfer problem comes down to the transfer of heat. "Cold" is not a physical manifestation in heat transfer; there is only the absence of heat.

So yes, you use all the same equations.

 

[kgmilano]

thank you for the help. it's highly appreciated. I'm able to calculate the amount of heat to be exracted in order to decrease water from 25 deg to 0 deg and the time it takes. but i don't know how to calculate the time with the aluminuim as the container.

 

[Mech_Engineer]

You'll have to calculate the thermal resistance of your aluminum container, and then set up a thermal-equivalent electrical circuit to solve the transient problem.

 

[alphy]

for reaching out! Heat transfer equations can definitely be a bit tricky, especially when dealing with cold temperatures. In this case, you can still use the standard heat transfer equations, but you will need to consider the fact that you are transferring cold instead of heat. This means that the direction of heat flow will be reversed, with the cold water transferring heat to the surrounding environment.

To determine the specific equations you will need to use, it will depend on the specific design and materials of your water dispenser. In general, for a cold water dispenser, you will need to consider conduction, convection, and possibly radiation as well. Conduction refers to heat transfer through a solid material, so you will need to consider the thermal conductivity of the aluminium casing. Convection refers to heat transfer through a fluid, so you will need to consider the flow of the cold water and how it interacts with the surrounding air. Radiation refers to heat transfer through electromagnetic waves, and may only need to be considered if your dispenser has a glass or clear plastic component.

Overall, it's important to carefully consider all factors and gather data on the materials and design of your dispenser in order to accurately calculate heat transfer. If you are struggling, it may be helpful to consult with a colleague or do some additional research on heat transfer equations specific to cold temperatures. Good luck with your project!