A DIY swamp cooler works by blowing air with a ducted fan into a cooler filled...
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● A DIY "swamp cooler" works by blowing air with a ducted fan into a cooler filled part way with water. The resulting evaporation cools down the water and the air flowing through the cooler. ● ME THE ATTE EU Assume the following specifications about the "swamp cooler" The fan blows in 5 m³ min-¹ of room air at Tin = 30°C and relative humidity in = 25% ● IGLOO KES+ E THERAPEY The flow from the fan onto the water can be approximated as an impinging jet with nozzle diameter D = 10 cm and height above the water Hj = 0.1 m. The surface area of the water in the cooler is A = 0.7 m². a. (9 pts) Calculate the average heat transfer coefficient for the jet impingement on the layer of water. Also calculate the average mass transfer coefficient for the jet impingement evaporation process. b. (10 pts) As evaporation proceeds, the overall pool of water cools down it reaches a steady temperature (Tw). Solve for the steady water temperature (Tw) and evaporation rate (mevap). To do this, simultaneously solve for the following three effects (I recommend using Engineering Equation Solver) The convective heat transfer between the air jet (Qconv) entering at Tin and the water at Tw. The convective mass transfer from the water interface to the air stream (mevap). Here, the vapor pressure at the water-air interface is Pint = Psat(Tw), and the bulk vapor pressure in the air can be determined with Tin and in- Energy conservation at the water-air interface, which is defined as: mevap hfg = Qconv c. (6 pts) Calculate the air outlet temperature assuming the air stream is cooled down by Qconv, and is well mixed as it exits the cooler. ● A DIY "swamp cooler" works by blowing air with a ducted fan into a cooler filled part way with water. The resulting evaporation cools down the water and the air flowing through the cooler. ● ME THE ATTE EU Assume the following specifications about the "swamp cooler" The fan blows in 5 m³ min-¹ of room air at Tin = 30°C and relative humidity in = 25% ● IGLOO KES+ E THERAPEY The flow from the fan onto the water can be approximated as an impinging jet with nozzle diameter D = 10 cm and height above the water Hj = 0.1 m. The surface area of the water in the cooler is A = 0.7 m². a. (9 pts) Calculate the average heat transfer coefficient for the jet impingement on the layer of water. Also calculate the average mass transfer coefficient for the jet impingement evaporation process. b. (10 pts) As evaporation proceeds, the overall pool of water cools down it reaches a steady temperature (Tw). Solve for the steady water temperature (Tw) and evaporation rate (mevap). To do this, simultaneously solve for the following three effects (I recommend using Engineering Equation Solver) The convective heat transfer between the air jet (Qconv) entering at Tin and the water at Tw. The convective mass transfer from the water interface to the air stream (mevap). Here, the vapor pressure at the water-air interface is Pint = Psat(Tw), and the bulk vapor pressure in the air can be determined with Tin and in- Energy conservation at the water-air interface, which is defined as: mevap hfg = Qconv c. (6 pts) Calculate the air outlet temperature assuming the air stream is cooled down by Qconv, and is well mixed as it exits the cooler.
Expert Answer:
Answer rating: 100% (QA)
ANSWER a 9 pts The average heat transfer coefficient for the jet impingement on the layer of water can be calculated using the following formula h 4 G L Pr D H Where h average heat transfer coefficien... View the full answer
Related Book For
Elementary Principles of Chemical Processes
ISBN: 978-0471720638
3rd Edition
Authors: Richard M. Felder, Ronald W. Rousseau
Posted Date:
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