Delhi Shower: Black or White Paint?

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SUMMARY

The discussion centers on the efficiency of painting a shower drum for optimal heat retention. The original setup involved a 50-gallon drum painted black on the outside and white on the inside. It is concluded that painting both the outside and inside black would maximize heat absorption and radiation efficiency. Additionally, considerations are made regarding the potential benefits of painting non-sunlit areas white to minimize heat loss, particularly in cooler climates like the UK.

PREREQUISITES
  • Understanding of heat transfer principles, specifically conduction and radiation.
  • Knowledge of thermal properties of materials, particularly paint colors and their effects on heat absorption.
  • Familiarity with practical applications of thermal efficiency in water heating systems.
  • Basic concepts of environmental factors affecting heat retention, such as sunlight exposure.
NEXT STEPS
  • Research the thermal properties of different paint colors and their impact on heat absorption.
  • Explore advanced heat transfer concepts, including conduction and radiation in fluid systems.
  • Investigate the design of solar water heaters and their efficiency optimization techniques.
  • Learn about insulation materials and methods to reduce heat loss in water storage systems.
USEFUL FOR

This discussion is beneficial for engineers, DIY enthusiasts, and anyone involved in designing or optimizing water heating systems, particularly in varying climates.

Jabordnick
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Back when I was a youngling, I was down in Delhi, tobacco picking. Our shower consisted of a 50 gallon drum with a faucet and showerhead sitting in the greenhouse. We painted the outside of it black to collect the heat and painted the inside white to radiate it. In retrospect I'm thinking we should have painted both the outside and inside black. I'm just wondering which would have been more efficient?
 
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Off hand I think the inside color wouldn't matter, since the heat transfer from the drum to the water would be primarily by conduction.
 
Black and black would maximise absorption on the outside and radiation on the inside. But, in this instance, mathman gives the correct practical answer.

It could be an advantage to have any parts of the tank which are never in the Sun painted white to reduce losses, if that's a relevant worry in Delhi. It could be relevant here in the chilly UK.
 

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