Heat transfer for a cold water dispensor.

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Discussion Overview

The discussion focuses on the heat transfer involved in designing a cold water dispenser, specifically addressing the equations and principles applicable when dealing with cold water. Participants explore the calculations necessary for cooling water from a specific temperature and the role of the aluminum container in this process.

Discussion Character

  • Technical explanation, Conceptual clarification, Experimental/applied

Main Points Raised

  • One participant inquires about the applicability of standard heat transfer equations for a cold water dispenser, questioning if "cold" affects the equations used.
  • Another participant asserts that heat transfer problems are fundamentally about the transfer of heat, indicating that "cold" is merely the absence of heat and that standard equations apply.
  • A participant expresses gratitude for the clarification and mentions being able to calculate the heat extraction needed to cool water from 25 degrees to 0 degrees but struggles with incorporating the aluminum container into the time calculations.
  • A later reply suggests calculating the thermal resistance of the aluminum container and setting up a thermal-equivalent electrical circuit to address the transient heat transfer problem.

Areas of Agreement / Disagreement

Participants generally agree on the applicability of standard heat transfer equations to the problem, but there is no consensus on the specific calculations involving the aluminum container and the time required for cooling.

Contextual Notes

Participants have not resolved the specific mathematical steps needed to incorporate the aluminum container into the cooling time calculations, and assumptions regarding the thermal properties of the materials have not been explicitly stated.

kgmilano
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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
 
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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.
 
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.
 
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.
 

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