Difference between Ideal and Real Vapour Cycle

This laboratory report discusses the difference between the ideal and real vapour cycle. It explains the concept of heat pumps and refrigeration, and compares theoretical results with practical outcomes. The report also includes graphs and measurements of pressure, temperature, and power. The conclusion highlights the differences in heat transfer and performance coefficients.

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LABORATORY REPORT
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Introduction
The main objective of conducting this lab and the experiment is to know the difference
that is there between the ideal and real vapour cycle. For a full understanding of this experiment
and to achieve the aims measurement of heat pumps cycles and real refrigeration are recorded
then a keen comparison is done to the theoretical results data. The heat pump is employed since
it has the same operational concept as the refrigerator which is the transfer of heat energy from a
low temperature to higher temperature (Kakaç, 2012). A refrigerator has four main parts that are
a condenser, a compressor, an evaporator and expansion valve. Primarily the evaporator will heat
the refrigerant with equal heat to enable it to change the fluid (refrigerant) state to saturated
vapour from saturated liquid.
Thereafter the refrigerant will move to the compressor when in gaseous form and it will
then be compressed to the pressure of the condenser. It will hence leave the compressor at a
higher temperature, cools down and then condenses while it flows in the coil of the condenser
through removing heat energy to the environment (McBrewster, 2010). Lastly, it will move to
the capillary tube a place where its temperature, as well as pressure, reduces significantly
because of the effects of the throttling. There will be low temperature in the refrigerant then the
low temperature will flow to the evaporator, at the evaporator, it will evaporate through
absorbing heat energy from the refrigerant space. The above-explained cycle is very complete
since the refrigerant leaves the evaporator and enter again in the compressor.
During the experiment, the Pressure and the temperature of the refrigerant are recorded
before and after entering every part and this will permit the hypothetical outcomes to be obtained
by a means of standard P-h graphs for the refrigerant (Silberstein, 2013). At the same time,
another strategy is employed to record the power of every device, generally using a watt meter

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that permits genuine measurements to be gotten (Wohlfarth, 2015). The most finding is the
practical outcomes realistic presumption like heat transfer in isothermal and isentropic
compression are employed to make calculations simpler.
RESULTS
i. H1 is recorded by means of a horizontal line being sketched at 1.5 bar pressure while the
measurement of the enthalpy value where these lines meet with a line of saturated vapour
at a100C.temperature.
ii. The sloping line moving via the first point of meeting is employed to obtain H2 that is the
next crossing point with the flat line of a pressure 8. 5 bar.
iii. H3 is recorded through measuring the point of crossing which is 8. 5 bar horizontal line
intersected with the liquid curve at saturated state.
iv. H3=H4 due to the effects of throttle which reduces the pressure at perpetual enthalpy.
v. H2 is recorded through the protracted 400C line to saturated vapour curve right side and
then measuring the enthalpy, this is the point where line intersected with 8. 5 bar
horizontal line.

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The first graph shown in figure 1 illustrates the exchange of heat in an evaporator
recorded by a watt meter and obtained through differences in enthalpy (Letcher, 2017). The watt
meter offers a several prominent and more precise estimation of power. This is due to differences
in enthalpy were obtained through values gotten from graphs physically while the watt meter
employing a computerized instrument to record power consumed. This meter provides a correct
readings since the fluid inside is marginally overhead that is not taken to account for through the
method of differences in enthalpy (Murthy, 2010).
The second graph outlines the transfer of heat through a condenser obtained through
differences in enthalpy and differences in the temperature water. Whereas obtaining the
power through differences enthalpy, nevertheless, in real life, it is marginally subcooled and thus
the transfer of heat obtained through the temperature of the water shall be higher (Banks, 2012).
In figure 3 it is illustrated that watt meter permits much bigger power yield value as
compared to the other two strategies. This is due to the presumption that the compressor
compresses the fluid isotopically nevertheless, there are a few formations of heat because of
friction that are absorbed through the environment (in air) / materials and the refrigerant. The
power meter records the transferred heat to materials /air and the fluid nevertheless, another
strategies don’t consider transfer of heat to the environment (Johnson, 2014).
From 4th figure above it is concluded that the coefficient of performance of the fridge and
the heat pump incremented exponentially having power setting percentage while as shown in 5th

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figure , the isentropic effectiveness diminishes exponentially having the increment in power
setting percentage.
From 6th figure it is deduced that the perfect vapour contrasts the experimental vapour
cycle because:
i. The gaseous liquid from the evaporator is marginally overheated.
ii. The cycle of compression isn't isentropic
iii. The fluid from the condenser is marginally overcooked.
When doing the calculation of heat transfer by the use of enthalpy differences three marvels were
not taken under consideration, these include:
i. The overheating of the gaseous liquid from the evaporator.
ii. The overcooling of the fluid out of the condenser.
iii. The warm exchange amid compression of the gaseous liquid from the evaporator.
Conclusion
When the experiment complete, it can be deduced that in real life evaporator utilizing
higher power to vaporize the liquid as compared to the perfect scenario because of overheating
of the vapour as shown in figure1. Essentially, the transfer of heat for the condenser is higher
when the temperature of water strategy was employed than differences in enthalpy since of the
subcooling of fluid that's not accounted whereas using enthalpy difference strategy. Moreover,
diverse approaches utilized to record the power of compressor shall provide dissimilar outcomes
due to errors which are not accounted for as well as the heat transfer to air and materials. At last,

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the performance coefficient of fridge and heat pump increases with power rate setting whereas
the isentropic effectiveness reduces with a power rating percentage.
Bibliography

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Banks, D., 2012. An Introduction to Thermogeology: Ground Source Heating and C. 2nd ed.
Hull: John Wiley & Sons.
Johnson, W., 2014. Refrigeration & Air Conditioning Technology. 1st ed. Stoke: Cengage
Learning.
Kakaç, S., 2012. Low Temperature and Cryogenic Refrigeration. 3rd ed. Manchester: Springer
Science & Business Media.
Letcher, T., 2017. Enthalpy and Internal Energy:: Liquids, Solutions and Vapours. 3rd ed. Hull:
Royal Society of Chemistry.
McBrewster, o., 2010. Enthalpy. 3rd ed. Hull: VDM Publishing.
Murthy, A. M. &., 2010. A Textbook of Engineering Physics. 1st ed. Chicago: Chand Publishing.
Silberstein, E., 2013. Pressure-Enthalpy Without Tears. 3rd ed. Chicago: ESCO Press.
Wohlfarth, C., 2015. CRC Handbook of Enthalpy Data of Polymer-Solvent Systems. 4th ed.
Stoke: CRC Press.

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