Heat capacity of a heating element, in a flow of air

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SUMMARY

The discussion focuses on calculating the heat capacity of a heating element in a flow of air, specifically through a heater matrix. Key variables include inlet and outlet temperatures, heater power, and air flow. The formula referenced from Engineering Toolbox states that power equals the temperature differential multiplied by flow volume, air density, and specific heat. It is crucial to consider the impact of air flow on the heater's surface temperature to prevent overheating and potential melting of the element.

PREREQUISITES
  • Understanding of thermodynamics principles, specifically heat transfer.
  • Familiarity with the formula for power calculation involving temperature differential, flow volume, air density, and specific heat.
  • Knowledge of the effects of air flow on heating elements and their thermal limits.
  • Basic understanding of safety mechanisms in electrical resistance heaters, such as thermostats.
NEXT STEPS
  • Research the specific heat capacity of air under varying humidity conditions.
  • Learn about the thermal properties of different heating element materials.
  • Investigate the design and function of safety thermostats in electrical resistance heaters.
  • Explore advanced heat transfer calculations in fluid dynamics, particularly in heating applications.
USEFUL FOR

Engineers, HVAC professionals, and anyone involved in the design and optimization of heating systems in air flow applications will benefit from this discussion.

James125
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Air is flowing through a pipe, through a heater matrix.

Flow, Inlet temperature and heater power vary. Is it possible to calculate the heat capacity of the matrix by using the Inlet & outlet temperatures, power & flow?

I'm assuming no heat loss to the pipe walls to make it easier, but I'm not sure how to do this.
 
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Please describe the actual configuration more completely and explain what you mean by heat capacity of the matrix .
 
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I want to work out the heat capacity of the heater and thus the temperature that it will be.

Heating.png
 
James125 said:
I want to work out the heat capacity of the heater and thus the temperature that it will be.

View attachment 211151
Reference from Engineering Toolbox
Power = temperature differential * flow volume * air density * specific heat. Keep in mind that specific heat is influenced by how much water vapor is in the air.

Also, consider that happens to the heater element when air flow falls below a certain point - surface temperature climbs as flow decreases - flow too low, and the element melts. To prevent this, electrical resistance space heaters often incorporate a safety thermostat clamped to the element surface.
 
James125 said:
I want to work out the heat capacity of the heater and thus the temperature that it will be.

View attachment 211151
Sure. Your opening post implies all of those are given though. So what is given and what do you want to calculate?
 

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