The Blueprint of Water

The Hero of Heat Transfer: Problem Set

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⟵ 02 The Hero of Heat Transfer (Engineering Notes) · Contents · 02 The Hero of Heat Transfer (Answer Key) ⟶

The Hero of Heat Transfer: Problem Set

“These are only provided to reinforce understanding. The Engineering Notes contain some of the information that will be required. Make sure to employ dimensional analysis for all unit conversions.”

Level 1: Conceptual Mastery

  1. What is the difference between adhesion and cohesion? Why does water need both for effective heat transfer?

  2. The chapter describes the Hydrogen-Bond Network as a “molecular shock absorber.” In your own words, explain what this means and why it gives water a high specific heat.

  3. What is the difference between sensible heat and latent heat? Which one changes temperature, and which one changes state?

  4. The chapter says “refrigerants are quitters by design.” What does this mean in terms of intermolecular forces and phase change, and how does it contrast with water?

Level 2: Applied Thinking

  1. How many BTUs are required to heat 500 gallons of water from 60°F to 180°F? (Convert gallons to pounds first.)

  2. How much energy is required to (a) heat 1 pound of water from 72°F to 212°F, and (b) completely vaporize that same pound of water at 212°F? How many times more energy does vaporization require than heating the water from 72°F to 212°F?

  3. A cooling tower removes 6,000,000 BTU/hr. How many pounds of water must evaporate per hour? Convert to GPM.

Level 3: System Integration

  1. Using the 1% evaporation rule of thumb, a tower recirculates 1,500 GPM with a 10°F temperature drop. Estimate the evaporation rate in GPM. Then verify your answer using the latent heat equation and Q = m × cₚ × ΔT.

  2. A boiler produces steam at atmospheric pressure. The feedwater enters at 50°F. How many total BTUs per pound are required to produce steam? Break your answer into the sensible heat portion and the latent heat portion.

  3. The chapter identifies three energy reservoirs in water: kinetic energy, potential energy stored in the Hydrogen-Bond Network, and phase-change energy. In 2–3 sentences, explain why all three reservoirs are necessary for water to function as both a boiler medium and a cooling medium.

Problem notes

Each problem as its own linked note.

2.1 · 2.2 · 2.3 · 2.4 · 2.5 · 2.6 · 2.7 · 2.8 · 2.9 · 2.10

⟵ 02 The Hero of Heat Transfer (Engineering Notes) · Contents · 02 The Hero of Heat Transfer (Answer Key) ⟶

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