An industrial facility must remove thermal energy from a hot fluid stream by using…
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
An industrial facility must remove thermal energy from a hot fluid stream by using either of two processes:
Process X: Condense 2.00 kg of steam at 100 °C to liquid water at 100 °C.
Process Y: Cool 2.00 kg of liquid water from 100 °C to 0 °C and then freeze it completely to ice at 0 °C.
Data (at 1 atm):
• Specific heat capacity of liquid water = 4.18 J g⁻¹ °C⁻¹
• Molar enthalpy of vaporization of water = 40.7 kJ mol⁻¹
• Molar enthalpy of fusion of water = 6.01 kJ mol⁻¹
• Molar mass of water = 18.0 g mol⁻¹
(a) Calculate the quantity of heat, in kJ, released by Process X.
(b) Calculate the quantity of heat, in kJ, released by Process Y.
(c) Identify which process releases more energy and determine the percentage by which it exceeds the other process.
(d) For large-scale operation the engineers prefer the single process that releases more energy. Describe one practical advantage, other than the energy quantity itself, that supports their choice.