Dr. M. Thirumaleshwar Applied Thermodynamics: Software Solutions Part-IV (Psychrometrics, Reactive systems) 2 Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) 1st edition © 2014 Dr. M. Thirumaleshwar & bookboon.com ISBN 978-87-403-0788-7 3 Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Contents Contents Dedication Part I Preface Part I About the Author Part I About the Software used Part I To the Student Part I How to use this Book? Part I 1 Gas Power Cycles Part I 1.1 Definitions, Statements and Formulas used[1-6]: Part I 1.2 Problems on Otto cycle (or, constant volume cycle): Part I 1.3 Problems on Diesel cycle (or, constant pressure cycle): Part I 1.4 Problems on Dual cycle (or, limited pressure cycle): Part I 1.5 Problems on Stirling cycle: Part I 1.6 References: Part I GET THERE FASTER Some people know precisely where they want to go. Others seek the adventure of discovering uncharted territory. Whatever you want your professional journey to be, Oliver Wyman is a leading global management consulting firm that combines you’ll find what you’re looking for at Oliver Wyman. deep industry knowledge with specialized expertise in strategy, operations, risk management, organizational transformation, and leadership development. With Discover the world of Oliver Wyman at oliverwyman.com/careers offices in 50+ cities across 25 countries, Oliver Wyman works with the CEOs and executive teams of Global 1000 companies. 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OUR WORLD 4 Click on the ad to read more Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Contents 2 Cycles for Gas Turbines and Jet propulsion Part II 2.1 Definitions, Statements and Formulas used[1-7]: Part II 2.2 Problems solved with Mathcad: Part II 2.3 Problems solved with EES: Part II 2.4 Problems solved with TEST: Part II 2.5 References: Part II 3 Vapour Power Cycles Part II 3.1 Definitions, Statements and Formulas used[1-7]: Part II 3.2 Problems solved with Mathcad: Part II 3.4 Problems solved with TEST: Part II 3.5 References: Part II 4 Refrigeration Cycles Part III 4.1 Definitions, Statements and Formulas used[1-7]: Part III 4.1.1 Ideal vapour compression refrigeration cycle: Part III 4.2 Problems solved with Mathcad: Part III 4.3 Problems solved with DUPREX (free software from DUPONT) [8]: Part III 4.4 Problems solved with EES: Part III 5 Click on the ad to read more Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Contents 4.5 Problems solved with TEST: Part III 4.6 References: Part III 5 Air compressors Part III 5.1 Definitions, Statements and Formulas used[1-6]: Part III 5.2 Problems solved with Mathcad: Part III 5.3 Problems solved with EES: Part III 5.4 References: Part III 6 Thermodynamic relations Part III 6.1 Summary of Thermodynamic relations [1-6]: Part III 6.5 References: Part III 7 Psychrometrics 8 7.1 Definitions, Statements and Formulas used [1-11]: 8 7.2 Problems solved with Mathcad: 31 7.3 Problems solved with Psychrometric chart: 62 7.4 Problems solved with EES: 73 7.5 Problems solved with TEST: 96 7.6 References: 141 In the past four years we have drilled 81,000 km That’s more than twice around the world. 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What will you be? careers.slb.com 6 Click on the ad to read more Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Contents 8 Reactive Systems 143 8.1 Definitions, Statements and Formulas used [1-11]: 143 8.2 Problems solved with Mathcad: 166 8.3 Problems solved with EES: 198 8.4 Problems solved with TEST: 228 8.5 References: 288 9 Compressible fluid flow Part V 9.1 Definitions, Statements and Formulas used Part V 9.2 Problems solved with Mathcad, EES and TEST Part V 9.3 References Part V Could you think of 101 new things to do with eggs and oil? Hellmann’s is one of Unilever’s oldest brands having been popular for over 100 years. If you too share a passion for discovery and innovation we will give you the tools and opportunities to provide you with a challenging career. Are you a great scientist who would like to be at the forefront of scientific innovations and developments? Then you will enjoy a career within Unilever Research & Development. For challenging job opportunities, please visit www.unilever.com/rdjobs. 7 Click on the ad to read more Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Psychrometrics 7 Psychrometrics Learning objectives: 1. In this chapter, ‘Psychrometrics’ i.e. is the study of properties of air-water vapor mixtures is dealt with. 2. We give the definitions of various terms and also the thermodynamic equations to determine various psychrometric properties. 3. Psychrometric chart, which is very useful to analyse psychrometric processes, is presented. 4. Various psychrometric processes adopted in air-conditioning are explained with the help of Psychrometric chart. 5. Two very good stand-alone calculators to quickly calculate various Psychrometric properties are explained. 6. Usefulness of Psychrometric chart is demonstrated by solving many problems. 7. Several very useful Functions are written in Mathcad to calculate various psychrometric properties. A summary of various Mathcad Functions written is also provided. 8. Also, many problems are solved in Mathcad, EES and TEST to illustrate the problem solving techniques in this chapter. ======================================================================= 7.1 Definitions, Statements and Formulas used [1-11]: 7.1.1 ‘Psychrometrics’ ‘Psychrometrics’ is the study of properties of air-water vapor mixtures. We also study various processes involving the air-water vapor mixtures and the important applications are in the fields of comfort air conditioning , paper and textile engineering processes etc. 7.1.2 Properties of atmospheric air: Atmospheric air is considered as a mixture of air and water vapor. Further, both air and water vapor are considered as ideal gases (without much error, i.e. less than 0.2%). Therefore: Atmospheric pressure: p = pa + pw, where pa = partial pressure of air, and pw = partial pressure of water vapor. 8 Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Psychrometrics Enthalpy of dry air: hair = cp.T = 1.005 * T, kJ/kg Δhair = cp. ΔT = 1.005 * ΔT, kJ/kg Enthalpy of water vapor: Enthalpy of water vapor at 0 C is 2500.9 kJ/kg. Average value of cp in the temp range -10 C to 50 C is 1.82 kJ/kg.C. Therefore, enthalpy of water vapor at temp T is determined as: hg(T) = 2500.9 + 1.82 * T, kJ/kg,… T in deg.C Total enthalpy of moist air: h(T) = 1.005 * T + w * (2500.9 + 1.82 * T), kJ/kg Sat. pressure of water vapor (psat): is related to the ‘dry bulb temp’ (i.e. the ordinary temp measured with a thermometer in atmospheric air. Sat. pressure of water with temp can be read from the Steam Tables [Ref: www.thermofluids.net – TEST Software] 9 Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Psychrometrics Following is the mathematical relation for the vapor pressure(Pa) of water with temp (deg.C) [11]: At T = 20 C, we get: psat = 2339 Pa, which matches very well with the above Table. Specific humidity or humidity ratio (w): is defined as: where p is the total pressure = atmospheric pressure = 101325 Pa Relative humidity (RH or φ): It is the ratio of amount of water vapor present in air to the max. amount of water vapor that it can hold at that temperature. 10 Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Psychrometrics Degree of saturation (μ): It is the ratio of actual specific humidity and the saturated specific humidity, both at the same temp T. For dry air, i.e. when φ = 0, we have: μ = 0, and For sat. air, i.e. when φ = 100%, we have: μ = 1, i.e φ varies between 0 and 1. Dew-point temperature (dpt): It is defined as the temp at which condensation begins when air is cooled at constant pressure. i.e. dpt is the sat. temp of water corresponding to the vapor pressure. i.e. dpt = Tsat at pw 11 Download free eBooks at bookboon.com Applied Thermodynamics: Software Solutions: Part-IV (Psychrometrics, Reactive systems) Psychrometrics Dew point temp (deg.C), between 0 and 70 C, as a function of partial pressure of water vapor in air (pw), is given by following eqn: Remember that pw is related to dry bulb temp and RH. So, dew point temp (dpt) can be written in terms of dry bulb temp (dbt) and RH. Dry bulb temperature (dbt): It is the temp measured with an ordinary thermometer placed in air. Wet bulb temperature (wbt): It is the temp measured by a thermometer when its bulb is enveloped with a cotton wick saturated with water and held in a flowing stream of air.