Thermodynamics heat transfer problem

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SUMMARY

The discussion focuses on a thermodynamics heat transfer problem involving an 85kg yachtsman losing body heat after falling into cold ocean waters. Key parameters include a 0.02m thick layer of surface fat, a surface heat transfer coefficient of 30, and a metabolic heat production rate of 180W. The initial core temperature is 36°C, while the ocean temperature is 5°C. Participants seek guidance on calculating the core temperature drop over 30 minutes, emphasizing the relationships between heat transfer rates, temperature differences, and the heat transfer coefficient.

PREREQUISITES
  • Understanding of heat transfer principles, including conduction and convection.
  • Familiarity with thermal conductivity and heat capacity concepts.
  • Knowledge of the heat transfer coefficient and its application in thermal problems.
  • Basic proficiency in solving differential equations related to temperature changes over time.
NEXT STEPS
  • Study the conduction equation and its application in multi-layer systems.
  • Learn about the principles of convection and how to calculate heat transfer coefficients.
  • Explore the concept of thermal resistance in layered materials.
  • Investigate the relationship between metabolic heat production and body temperature regulation.
USEFUL FOR

This discussion is beneficial for students in thermodynamics, particularly those studying heat transfer, as well as professionals in fields related to thermal management and body heat regulation.

luysion
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Homework Statement



An 85kg yachtsman falls out of his boat into the cold ocean waters. He begins to loose body heat through a 0.02m thick layer of surface fat. The surface heat transfer coefficient between his skin and the sea water is 30. The total surface area of the yachtsman is 2.2 and his metabolism continues to produce thermal energy at a rate of 180W. if the initial core temperature of the yachtsman is 36deg and the ocean water is at 5deg by how much will his core body temperature fall in the 30minutres before he is rescued ? (in K)
Thermal conductivity of surface fat = 0.2
heat capacity of human body = 3.49x10^3


Homework Equations





The Attempt at a Solution



Hey. I got an exam tomorrow and I am really confused as to answer this question. Like i don't understand what to calculate.. (conduction equation,convection etc) and how to deal with situations in which there are multiple layers (conduction through series I THINK), can someone please show me their working out and how they answer this question cheers.
 
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Break it into sections. How is the heat transfer rate linked with the changing core temperature over time? How is the same rate linked with the temperature difference across the fat layer? How is the same rate linked with the heat transfer coefficient to the water?
 

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