Name: Ma. Jennefer S. Caliboso
Course & Section: BSABE 3
2024
Date Performed: May 06, 2024
Date Submitted: May 25,
PABE07 AB PRODUCTS PROCESSING AND STORAGE
Laboratory Exercise No. 3
Psychrometry
Introduction:
According to (Purushothama, 2009), psychrometry is the art of measuring the
moisture content of the air. The systematized knowledge that investigates the thermal
properties of moist air, considers the measurement and control of the moisture content of
air, and studies the effects of moisture on material and human comfort, may be called
psychometrics.
In this laboratory, we will determine the wet bulb and dry bulb temperatures of
ambient and conditioned air by the use of a sling psychrometer. A sling psychrometer is
used to measure the wet and dry bulb temperatures to know the relative humidity and the
dew point temperature. At the end of this laboratory, the students will know the importance
of using a psychrometer in a real-life situation, wherein we can apply this on a day-to-day
basis.
Objectives:
This exercise aims to evaluate different properties of moist air in various
conditions
Methodology
In this laboratory exercise, we used a sling psychrometer to determine the wet
and dry bulb temperature. To measure the wet bulb temperature, we set a timer for 3
minutes, and we moved the sling psychrometry in a circular motion, after that, we used
a pen and paper to record the gathered data. While in measuring the wet bulb
temperature, first, we soaked the cotton wick in water, and after that, same process as
the dry bulb, we moved it in a circular motion for 3, and the wet and dry bulb was done
in 3 trials to get the average temperature of the ambient and conditioned air.
I also used a psychrometric chart to determine other properties of the air in the
two rooms such as relative humidity, enthalpy, humidity ratio, and specific volume.
Additionally, we will acquire the temperature and humidity ratio difference between the
two rooms.
Location of Air
Dry bulb temperature
Wet bulb temperature
Ambient Air
37
37.5
37
27
27.5
27
Conditioned air
26.5
27
28
19.5
19
19
By getting the average Tdb and Twb, you just add the 3 trials and divide by the
number of trials which is 3. The average dry and wet bulb temperature of ambient air is,
37.17C and 27.17C respectively, while for the conditioned air, the dry and wet bulb
temperature is 27.17C and 19.17C. By using the psychometric chart, I determined the
other properties of air like specific volume, enthalpy, and humidity ratio.
For Ambient air
For conditioned air
Dry Bulb Temperature
37.17C
27.17C
Wet Bulb Temperature
27.17C
19.17C
Specific volume
0.912𝑚3
𝑘𝑔
0.868m^3/kg
enthalpy
96.9KJ/kg
59.8KJ/kg
Humidity Ratio
23.9g/kg
12.98g/kg
Knowing the psychrometric properties is important for creating comfortable indoor
environments and efficient air systems. Dry bulb temperature tells us how hot or cold the
air is, while wet bulb temperature indicates both heat and moisture levels, critical for
knowing humidity and cooling systems. Specific volume helps design ventilation systems,
enthalpy determines energy needs for heating or cooling, and humidity ratio informs about
water vapor levels, vital for drying and indoor moisture control. We can use these data for
a better output of the product
The relevance of getting the temperature and humidity of the two rooms is that
checking the temperature of both the ambient and conditioned air in both rooms is super
important. It helps us make sure people feel comfy, keeps energy use in check, controls
humidity levels, and ensures our products stay in top shape. By comparing temperatures,
we can see how well the air conditioning is working and make adjustments to keep
everyone happy and everything running smoothly.
Lifelong Learnings
In this laboratory exercise, I learned that getting the property of air will help us in
designing the right layout for the project. Honestly speaking, I just know how to identify
and solve a problem about psychrometry but I do not know the application of this in a
real-life situation. As an agricultural and biosystems engineering student, I appreciate
this lesson because this just not only taught me theoretically but also in reality. I just
recently learned, because of this laboratory exercise the importance of design
calculations, and I appreciate the beauty of taking this course. Also, I would like to take
this opportunity to thank you ma’am because you made our subject enjoyable and not
too heavy to catch up on.
References
Purushothama. (2009). Psychrometrics. Science Direct,
https://www.sciencedirect.com/topics/engineering/psychrometrics#:~:text=The%2
0art%20of%20measuring%20the,comfort%2C%20may%20be%20called%20psy
chrometrics.