HW01 - Equivalent Environmental Temperature and Thermal...

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Equivalent Environmental Temperature and Thermal Comfort BEE 1510: Introduction to Computer Programming Homework Exercise 01 Timothy Lin Cornell University due: September 18, 2008 1
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Executive Summary This project was based in the field of engineering biophysics, more specifically human engineering. Organisms exchange heat with their environments by simple convection, evaporation of perspiration and thermal radiation exchange. These kinds of situations are often “abstracted,” or described by equations. One simple model is to define “virtual” temperatures that will lead to a numerical value of the rate of heat exchange. The equivalent temperature of air is the virtual temperature that would cause the same rate of heat exchange if only convective exchange were to occur. The equivalent temperature of a surface is the virtual temperature to which a surface must be raised if the sum of sensible and latent heat exchange occurs by convection of sensible heat only. Water vapor saturation partial pressure reflects the greatest amount of moisture that can be held by air at saturation. Water vapor actual partial pressure is the actual pressure of water vapor in the air when the relative humidity is not 100%. Those are the various terms used in the script and accompanying program. The objective of this project is to calculate the various values of saturated vapor pressure, actual vapor pressure, equivalent temperatures, and the thermal sensation values using given values of air temperature and relative humidity. Materials and Methods The first equation used is in the program written to figure out the saturated vapor pressure. It is pws = exp(A1/T + A2 + A3*T + A4*T^2 + A5*T^3 + A6*T^4 + A7*log(T)), where pws = saturation partial pressure in kilopascals (converted by script after program) and T = temperature in Kelvin. The second equation used is to calculate the actual partial pressure in kilopascals. It is rh*pws, where rh is the relative humidity in decimal form. The third equation calculates equivalent temperature. It is t+pw/y, where t is the air temperature in degrees Celcius and y is a parameter explained in the algorithm. In addition, when calculating the thermal sensation values, there are six other equations that are in the algorithm for a female at 1, 2 and 3- hour intervals and the same for a male. 2
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Materials and Methods – algorithm for script 1. Enter Comments BEE 1510 Introduction to Computer Programming Homework Assignment 1 Timothy Lin 2. Inputs i. Define Variables pws = saturation partial pressure (pascals) pw = actual partial pressure (kPa) t = temperature of air (Celcius) rh = relative humidity et = equivalent temperature of air (Celcius) F1 = thermal sensation value for female, 1 hour F2 = thermal sensation value for female, 2 hours F3 = thermal sensation value for female, 3 hours M1 = thermal sensation value for male, 1 hour M2 = thermal sensation value for male, 2 hours M3 = thermal sensation value for male, 3 hours
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HW01 - Equivalent Environmental Temperature and Thermal...

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