advertisement

Psychrometrics

67 %
33 %
advertisement
Information about Psychrometrics
Education

Published on February 19, 2008

Author: kalyansg

Source: slideshare.net

Description

Use of psychrometric chart for analyzing air conditioning systems
advertisement

Psychrometrics & Air Conditioning Design Kalyan Chatterjea

Introduction to Comfort Air-conditioning

Introduction - Psychrometry The air conditioning processes are best understood by studying Psychrometry. Psychrometry is the study of atmospheric air and its associated water vapour. A psychrometric chart presents physical and thermal properties of moist air in a graphical form.

The air conditioning processes are best understood by studying Psychrometry.

Psychrometry is the study of atmospheric air and its associated water vapour.

Psychrometry – Dry Bulb Temp Dry-bulb temperature (DBT) is the commonly measured temperature from a thermometer.

Dry-bulb temperature (DBT) is the commonly measured temperature from a thermometer.

Psychrometry – Wet Bulb Temp Wet Bulb Temperature (WBT) is determined when air is circulated past a wetted sensor tip. Intersection of DBT and WBT provides the status point.

Wet Bulb Temperature (WBT) is determined when air is circulated past a wetted sensor tip.

Intersection of DBT and WBT provides the status point.

Psychrometry – Saturation Line Saturation line is a temperature condition at which water will begin to condense out of moist air. It is also called the dew point temperature line.

Saturation line is a temperature condition at which water will begin to condense out of moist air.

It is also called the dew point temperature line.

Psychrometry – Relative Humidity Relative Humidity (RH) is a ratio between actual moisture content of the air compared with the moisture content of the air required for saturation at the same temperature. RH is affects human comfort significantly. Sensible heat removal with increase in RH

Relative Humidity (RH) is a ratio between actual moisture content of the air compared with the moisture content of the air required for saturation at the same temperature.

RH is affects human comfort significantly.

Psychrometry – Specific Volume Specific Volume indicates the space occupied by air. This is useful in converting volumetric flow to mass-flow rate calculation.

Specific Volume indicates the space occupied by air.

This is useful in converting volumetric flow to mass-flow rate calculation.

Psychrometry - Enthalpy Enthalpy is the energy content of dry air & moisture expressed in kJ/kg of dry air. The information is useful is sizing up heating & cooling coils.

Enthalpy is the energy content of dry air & moisture expressed in kJ/kg of dry air.

The information is useful is sizing up heating & cooling coils.

Psychrometry – Sensible Heat Processes Heating & Cooling process – addition or removal of sensible heat without change in absolute moisture content. But RH changes as temperature changes.

Heating & Cooling process – addition or removal of sensible heat without change in absolute moisture content.

But RH changes as temperature changes.

Psychrometry - Dehumidification Dehumidification by cooling – in cooling coils temp of air reduces and the saturation point (dew point) is reached. Further cooling results in reduction of absolute humidity.

Dehumidification by cooling – in cooling coils temp of air reduces and the saturation point (dew point) is reached.

Further cooling results in reduction of absolute humidity.

Psychrometry – Comfort Zone Comfort Zone – statistical studies have been performed on large numbers of subjects of all ages, sexes and nationalities to arrive at a quantitative description of human comfort.

Comfort Zone – statistical studies have been performed on large numbers of subjects of all ages, sexes and nationalities to arrive at a quantitative description of human comfort.

Comfort zone … comfort is a very subjective term! Statistically, majority of human beings are comfortable when temp is between 18-22 0 C and RH is 40-65% Psychrometry – Comfort Zone

Comfort zone … comfort is a very subjective term!

Statistically, majority of human beings are comfortable when temp is between 18-22 0 C and RH is 40-65%

Psychrometry – Climate Classification Climate Classification shows the various approximate zones of temperature and humidity on the psychrometric chart.

Climate Classification shows the various approximate zones of temperature and humidity on the psychrometric chart.

Psychrometry – Heating at Sea Heating without humidification at sea . Sensible heat addition with decrease in RH…away from comfort zone

Heating without humidification at sea .

Psychrometry – Heating at Sea Heating with humidification at sea . Heat addition with humidification resulting in more comfortable RH

Heating with humidification at sea .

Heating Process in Detail Process showing sensible heat addition.

Process showing sensible heat addition.

Heating Process in Detail Applying the SFEE h-values can be directly read from the psychrometric chart

Applying the SFEE

Process showing sensible heat cooling, followed by Further cooling, which leads to precipitation. Cooling & Dehumidification in Detail

Process showing sensible heat cooling, followed by

Further cooling, which leads to precipitation.

Cooling & Dehumidification in Detail Applying the SFEE Mass flow balance equation for the water & steam In practice, water mass flow is very small compared to air mass flow. So a simpler equation could be used without undue error.

Applying the SFEE

References Psychrometric Chart Download http://www.ent.ohiou.edu/~thermo/me328/quiz.info/Nautica_SI.pdf

Psychrometric Chart Download

http://www.ent.ohiou.edu/~thermo/me328/quiz.info/Nautica_SI.pdf

References

References Overview of Psychrometrics: http://www.handsdownsoftware.com/Overview_of_Psychrometrics.pdf

Overview of Psychrometrics:

http://www.handsdownsoftware.com/Overview_of_Psychrometrics.pdf

References

References Coil Load Calculations: http://courses.washington.edu/me425/425%20Psychrometric%20Review%202007.pdf

Coil Load Calculations:

http://courses.washington.edu/me425/425%20Psychrometric%20Review%202007.pdf

References

References Glossary: http://air.1800anytyme.com/info/air_conditioning_glossary.php

Glossary:

http://air.1800anytyme.com/info/air_conditioning_glossary.php

References

References Standard: British Standards Institution QC100.B862 BS EN ISO 2006 Ship and Marine Technology - Air-conditioning & Ventilation of Accommodation Spaces - Design Conditions & Basis of Calculations

Standard: British Standards Institution QC100.B862 BS EN ISO 2006

Ship and Marine Technology - Air-conditioning & Ventilation of Accommodation Spaces - Design Conditions & Basis of Calculations

References

References Thermodynamic Expert System http://energy.sdsu.edu/testcenter/testhome/index.html TEST - a visual platform to analyze thermo-fluids problems, verify hand calculations, pursue what-if scenarios, visualize thermal systems, and engage in a life-long journey to master thermodynamics. Developed by Dr. S. Bhattacharjee, San Diego State University.

Thermodynamic Expert System

http://energy.sdsu.edu/testcenter/testhome/index.html

References

References ABS Guide for Crew Habitability on Off-shore Installations, 2002 "habitability" is defined as the acceptability of conditions of an offshore installation in terms of vibration, noise, indoor climate and lighting, as well as physical and spatial characteristics, according to prevailing research and standards for human efficiency and comfort

ABS Guide for Crew Habitability on Off-shore Installations, 2002

"habitability" is defined as the acceptability of conditions of an offshore installation in terms of vibration, noise, indoor climate and lighting, as well as physical and spatial characteristics, according to prevailing research and standards for human efficiency and comfort

References

References Simulation Hui, S. C. M. and K. P. Cheung, 1998. Application of building energy simulation to air-conditioning design, In Proc. of the Mainland-Hong Kong HVAC Seminar '98 , 23-25 March 1998, Beijing, pp. 12-20. http://www.arch.hku.hk/~cmhui/hvac98b.pdf

Simulation

Hui, S. C. M. and K. P. Cheung, 1998. Application of building energy simulation to air-conditioning design, In Proc. of the Mainland-Hong Kong HVAC Seminar '98 , 23-25 March 1998, Beijing, pp. 12-20.

http://www.arch.hku.hk/~cmhui/hvac98b.pdf

References

Thank You!

Add a comment

Related presentations

Related pages

Psychrometrics - Wikipedia, the free encyclopedia

Psychrometrics or psychrometry or hygrometry are terms used to describe the field of engineering concerned with the determination of physical and ...
Read more

Psychrometrics | ashrae.org

Learn more about Psychrometrics at ashrae.org. Login. ... Create psychrometric processes by plotting points then connecting them with process lines.
Read more

Psychometrics - Wikipedia, the free encyclopedia

Not to be confused with psychrometrics, ... More recently, psychometric theory has been applied in the measurement of personality, attitudes, ...
Read more

Psychrometrics, Level 1: Introduction - Sigler Wholesale ...

PSYCHROMETRICS, LEVEL 1: INTRODUCTION Psychrometrics 2 The formulas that were developed were plotted on a chart that is the psychrometric chart.
Read more

Psychrometric Calculator Online

Calculate online thermodynamic properties of moist (humid) air. ... Psychrometrics The site provides a feature rich, professional quality Psychrometric ...
Read more

Psychrometrics Theory and Applications - University of Arizona

9/18/2012 1 Psychrometrics Theory and Applications Dr. Murat Kacira, Associate Professor Agricultural and Biosystems Engineering Controlled Environment ...
Read more

Psychrometrics - Kraemer & Co. Mfg., Inc.

Psychrometrics is the measurement of the heat and water vapor properties of air. Commonly used psychrometric variables are temperature, ... Psychrometric Chart
Read more

Air Psychrometrics - Engineering ToolBox

Air Psychrometrics The study of moist and humid air - air condition - psychrometric charts, Mollier diagrams, air temperature, absolute and relative ...
Read more

Psychrometric Charts | Sustainability Workshop

Psychrometric charts indicate data points for each location they are representing. ... climate, psychrometrics. Links and References. Psychrometric Charts.
Read more

Psychrometric Calculator

Home; Calculator; Help; Register; About Psych... Free Gadgets; HVAC Videos; Contact Us
Read more