Chapter 12: Problem 10
Why does your bathroom mirror often fog up when you shower?
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Chapter 12: Problem 10
Why does your bathroom mirror often fog up when you shower?
These are the key concepts you need to understand to accurately answer the question.
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Moist air at \(20^{\circ} \mathrm{C}, 1 \mathrm{~atm}, 43 \%\) relative humidity and a volumetric flow rate of \(900 \mathrm{~m}^{3} / \mathrm{h}\) enters a control volume at steady state and flows along a surface maintained at \(65^{\circ} \mathrm{C}\), through which heat transfer occurs. Liquid water at \(20^{\circ} \mathrm{C}\) is injected at a rate of \(5 \mathrm{~kg} / \mathrm{h}\) and evaporates into the flowing stream. For the control volume, \(\dot{W}_{\mathrm{cv}}=0\), and kinetic and potential energy effects are negligible. Moist air exits at \(32^{\circ} \mathrm{C}, 1 \mathrm{~atm}\). Determine (a) the rate of heat transfer, in \(\mathrm{kW}\). (b) the rate of entropy production, in \(\mathrm{kW} / \mathrm{K}\).
Using methods in the most current \(A S H R A E\) Handbook of HVAC Applications, estimate the rate of evaporation from the surface of an Olympic-size swimming pool. The swimming hall is maintained at \(30^{\circ} \mathrm{C}\) with a dew point temperature of \(21^{\circ} \mathrm{C}\). Based on your estimate, determine the load, in \(\mathrm{kW}\), that the added moisture places on the air-conditioning system. Write a memorandum that summarizes your analysis and include at least three references.
An air-handling system is being designed for a \(12 \mathrm{~m} \times\) \(12 \mathrm{~m} \times 2.5 \mathrm{~m}\) biological research facility that houses 3000 laboratory mice. The indoor conditions must be maintained at \(24^{\circ} \mathrm{C}, 60 \%\) relative humidity when the outdoor air conditions are \(32^{\circ} \mathrm{C}, 70 \%\) relative humidity. Develop a preliminary design of an air-conditioning and distribution system that satisfies National Institute of Health (NIH) standards for animal facilities. Assume a biological safety level of one (BSL-1), and that two thirds of the floor space is devoted to animal care. Since an interruption in ventilation or air conditioning could place the laboratory animals under stress and compromise the research under way in the facility, account for redundancy in your design.
Moist air at \(25^{\circ} \mathrm{C}, 1 \mathrm{~atm}\), and \(40 \%\) relative humidity enters an evaporative cooling unit operating at steady state consisting of a heating section followed by a soaked pad evaporative cooler operating adiabatically. The air passing through the heating section is heated to \(43^{\circ} \mathrm{C}\). Next, the air passes through a soaked pad exiting with \(40 \%\) relative humidity. Using data from the psychrometric chart, determine (a) the humidity ratio of the entering moist air mixture. (b) the rate of heat transfer to the moist air passing through the heating section, in \(\mathrm{kJ}\) per kg of mixture. (c) the humidity ratio and temperature, in \({ }^{\circ} \mathrm{C}\), at the exit of the evaporative cooling section.
Write a report explaining the way the human body regulates its temperature, both under cold and hot climate conditions. Based on these thermoregulation mechanisms, discuss designs of personal protective clothing for fire fighters and other first responders. How are such clothing systems designed to provide protection against chemical or biological agents while maintaining sufficient thermal comfort to allow for strenuous physical activity? Include in your report at least three references.
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