Report: Energy Performance Characteristics of a Refrigeration System

This report analyzes the energy performance of a refrigeration system, focusing on thermal power dissipation and energy efficiency ratio (EER) calculations under varying condenser and evaporation temperatures. The study begins with an executive summary outlining the function of commercial reciprocating chillers and their components. It then delves into the methodology, including p-h and schematic diagrams, and proceeds to calculate thermal power dissipation for three different condenser temperatures (300°C, 350°C, and 400°C) across a range of evaporation temperatures. The report also calculates and plots the EER and Coefficient of Performance (COP) for each condenser scenario, providing a graphical representation of the relationships between these parameters. The report concludes with a discussion of the performance characteristics and their implications for system design and optimal operation, referencing relevant thermodynamic principles and finite-time thermodynamic analysis.

1
Energy performance of the refrigeration system
Refrigeration system

2
Energy performance of the refrigeration system
Contents
Executive summary.....................................................................................................................................3
Introduction.................................................................................................................................................4
Methodology...............................................................................................................................................6
p-h diagram.................................................................................................................................................6
schematic diagram of standard vapour compression system..................................................................6
Performance curve......................................................................................................................................7
Calculate and plot other characteristics (efficiencies).................................................................................8
Thermal Power........................................................................................................................................8
Thermal power dissipation for 1st condenser of 300C..........................................................................8
Thermal power dissipation for 2nd condenser of 350C.........................................................................9
Thermal power dissipation for 3rd condenser of 400C........................................................................10
Graphical presentation of the Thermal power dissipation against evaporation temperature..............11
Energy Efficiency Ratio - EER.....................................................................................................................12
Energy efficiency ratio for 1st condenser of 300C.............................................................12
Energy efficiency ratio for 2nd condenser of 350C............................................................14
Energy efficiency ratio for 3rd condenser of 400C............................................................17
Calculation of Carnot COP for the three types of condensers.........................................20
COP for the first condenser with condensing temperature of 300C..........................20
COP for the first condenser with condensing temperature of 350C..........................22
COP for the first condenser with condensing temperature of 450C..........................23
Graphical presentation of COP against Tc (0C)......................................................................25
Discuss the performance characteristics of the system and their implications with respect to system
design and optimal operation....................................................................................................................26
References.................................................................................................................................................28

3
Energy performance of the refrigeration system
Executive summary
The commercial reciprocating chiller is an advance electronic equipment that uses its ability to
removes heat from liquid using vapor-compression technology, which is the method by which a
commercial reciprocating chiller's compressor evaporates heat from the refrigerant, and since
they contain the reciprocating compressors it uses pistons to compress the refrigerant and the
liquid, which causes heat evaporation in the piston chamber, all this will facilitate a reduction in
the temperature of liquids for industrial applications.
Above all commercial reciprocating chillers utilize four main components; that is a compressor,
an evaporator, a condenser and a metering device. In addition, it operates with a closed-loop
system, this means that the coolant will have to remain in the chiller and it will be recycled
across many uses. The importance of this closed-loop commercial reciprocating chillers is that, it
contains a separate tank that filters and cleans the coolant before returning it to the main storage
area for re-use.
In summary, commercial reciprocating chillers uses a chemical refrigerant to absorb heat and
remove it from the liquid being chilled. With Freon refrigerants being the most used.

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Energy performance of the refrigeration system
Introduction
Majorly restriction has been injected by the Standard thermodynamics on the thermodynamic
measures and all this is grounded on reversible assumptions, which will mean either a zero rate
of operation or infinite system size. The extension of thermodynamic analysis in order to include
the finite time constraints was facilitated by the finite time thermodynamic, which derives a more
accurate restriction on the performance. This method of finite time thermodynamic has been used
majorly in several thermodynamic systems. Previously the heat engines were used extensively,
with maximum power efficiency production expression that is derived from two heat reservoirs
at temperatures and under the limitation of Newtonian heat transfer which is given by
expression;
ȠCA = 1- √ Tc
Th
The invention of reciprocating chillers lead to analysis and its characteristics was compared to
experimental data. The heat leakage and friction on the performance in line with engines were
totally addressed and the features were described using either power degradation or power
coefficient of performance coordinates.
Numerous objective functions have been proposed. Where combination of both maximization of
power with maximization of losses (entropy production)
Extensive merit has been observed through ecological coefficient of performance which is
defined as the ratio of the cooling load to the rate of availability loss (or entropy generation rate).
The present study of the finite-time analysis of refrigeration or heat pump systems, has an
inclusion of friction, solid, and fluid, with an aim of increasing the importance of source of
dissipation.
The characteristics are shown in graph of the cooling rate (r) versus coefficient of performance
(ω) coordinates, from this observation a comparison is drawn to the characteristics of real
refrigeration or heat pump devices, which later results to a proposal an estimation of
temperatures of the working fluid of the hot and cold side.

5
Energy performance of the refrigeration system
0 2 4 6 8 10 12
0
2
4
6
8
10
12
Coefficient of performance (ω)
cooling rate (r)
Fig 1; cooling rate versus coefficient of performance.
The presentation of the finite heat transfer rate is the sole source of heat losses [the dashes
curved]
The four limiting types of operation includes;
i. Open circuit in which both (r) and (ω) vanishes in the limit of slow operation
ii. Short circuit in which both (r) and (ω) vanishes but the limit of fast operation
iii. Maximum (r)
iv. Maximum both (ω)

6
Energy performance of the refrigeration system
Methodology
p-h diagram
0 50 100 150 200 250 300 350
0
2
4
6
8
10
12
14
16
Chart Title
Enthalpy kJ/kg
pressure (bars)
schematic diagram of standard vapour compression system

7
Energy performance of the refrigeration system
Task 1
Performance curve
30 28 26 24
0
10
20
30
40
50
60
30 35 40
outlet water temperature
cooling capacity (Kw)
2 4 8 12
0
1
2
3
4
5
6
7
8
9
30 35 40
evaporation temperature
power consumption (Kw)

8
Energy performance of the refrigeration system
30 28 26 24
0
5
10
15
20
25
30
35
40
45
30 35 40
evaporation temperature
heating capacity (Kw)
Task 2

9
Energy performance of the refrigeration system
Calculate and plot other characteristics (efficiencies)
Thermal Power
The calculation of the thermal power of a hydraulic system is based on the mass flow rate, the
heat capacity of the medium, and the temperature difference before and after heat dissipation.
Thermal power dissipation for 1st condenser of 300C
Pth = M*C* ∆ T *1000
M = mass flow rate = 0.0032 m3/s
C = 4.185 kJ/Kgk
Evaporation temperature = 50C
∆ T = 300C – 50C = 25 K
Pth = 0.0032*4.185 kJ/kg/K *25 K *1000
= 334.8 kJ
Evaporation temperature = 60C
∆ T = 300C – 60C = 24 K
Pth = 0.0032*4.185 kJ/kg/K *24 K *1000
= 321.41 kJ
Evaporation temperature = 70C
∆ T = 300C – 70C = 23 K
Pth = 0.0032*4.185 kJ/kg/K *23 K *1000
= 308.016 kJ
Evaporation temperature = 80C
∆ T = 300C – 80C = 22 K
Pth = 0.0032*4.185 kJ/kg/K *22 K *1000
= 294.624 kJ
Evaporation temperature = 90C
∆ T = 300C – 90C = 21 K
Pth = 0.0032*4.185 kJ/kg/K *21 K *1000
= 281.232 kJ
Evaporation temperature = 100C

10
Energy performance of the refrigeration system
∆ T = 300C – 100C = 20 K
Pth = 0.0032*4.185 kJ/kg/K *20 K *1000
= 267.84 kJ
Thermal power dissipation for 2nd condenser of 350C
Pth = M*C* ∆ T *1000
M = mass flow rate = 0.0032 m3/s
C = 4.185 kJ/Kgk
Evaporation temperature = 50C
∆ T = 350C – 50C = 30 K
Pth = 0.0032*4.185 kJ/kg/K *30 K *1000
= 401.76 kJ
Evaporation temperature = 60C
∆ T = 350C – 60C = 29 K
Pth = 0.0032*4.185 kJ/kg/K *29 K *1000
= 388.37 kJ
Evaporation temperature = 70C
∆ T = 350C – 70C = 28 K
Pth = 0.0032*4.185 kJ/kg/K *28 K *1000
= 374.98 kJ
Evaporation temperature = 80C
∆ T = 350C – 80C = 27 K
Pth = 0.0032*4.185 kJ/kg/K *27 K *1000
= 361.58 kJ
Evaporation temperature = 90C
∆ T = 350C – 90C = 26 K
Pth = 0.0032*4.185 kJ/kg/K *26 K *1000
= 348.19 kJ

11
Energy performance of the refrigeration system
Evaporation temperature = 100C
∆ T = 350C – 100C = 25 K
Pth = 0.0032*4.185 kJ/kg/K *25 K *1000
= 334.8 kJ
Thermal power dissipation for 3rd condenser of 400C
Pth = M*C* ∆ T *1000
M = mass flow rate = 0.0032 m3/s
Evaporation temperature = 50C
∆ T = 400C – 50C = 35 K
Pth = 0.0032*4.185 kJ/kg/K *35 K *1000
= 468.72 kJ
Evaporation temperature = 60C
∆ T = 400C – 60C = 34 K
Pth = 0.0032*4.185 kJ/kg/K *34 K *1000
= 455.328 kJ
Evaporation temperature = 70C
∆ T = 400C – 70C = 33 K
Pth = 0.0032*4.185 kJ/kg/K *33 K *1000
= 441.94 kJ
Evaporation temperature = 80C
∆ T = 400C – 80C = 32 K
Pth = 0.0032*4.185 kJ/kg/K *32 K *1000
= 428.54 kJ
Evaporation temperature = 90C
∆ T = 400C – 90C = 31 K
Pth = 0.0032*4.185 kJ/kg/K *31 K *1000
= 415.152 kJ

12
Energy performance of the refrigeration system
Evaporation temperature = 100C
∆ T = 400C – 100C = 30 K
Pth = 0.0032*4.185 kJ/kg/K *30 K *1000
= 401.76 kJ
Graphical presentation of the Thermal power dissipation against
evaporation temperature
4 5 6 7 8 9 10 11
0
50
100
150
200
250
300
350
400
450
500
Thermal power dissipation for 1st
condenser of 300C
Thermal power dissipation for 2nd
condenser of 350C
Thermal power dissipation for 3rd
condenser of 400C2
evaporation temperature 0C
power dispation
Energy Efficiency Ratio - EER
The Energy Efficiency Ratio - EER - is the cooling efficiency of unitary air-conditioning and heat
pump system.
The efficiency is always determined at a single rate of condition specified by an appropriate
equipment standard and is defined as the ratio of net cooling capacity - or heat removed to the
total input rate of electric power applied in Watts.