IJCRR - 9(8), April, 2017
Pages: 44-47
Date of Publication: 01-May-2017
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Reliability Measurement Technique for Evaporator used in Domestic Refrigerators
Author: Vivek Dwivedi, Praveen Pandey
Category: Technology
Abstract:Introduction: The evaporator used in domestic refrigerator is a heat exchanger in which the heat exchanging occurs by the mean of air. In general the reliability of evaporator is considerably high. It is seen the technical problems arising in evaporator is comparatively lesser than the other components used in it such as compressor, condenser and filter drier etc. But during long run of its use the problems arise in different components of evaporator such as due to leakage of refrigerant, choking or blockage of evaporative coil etc.
Aim and Objectives: The aim is to find the reliability of evaporator used in domestic refrigerators, working on the principle of vapour compression refrigeration system.
Material and Methods: The data used for analysis is collected from a reliable workshop and a system dynamic method is used for the analysis on Vensim-PLE modeling software.
Result: In result output table for year wise reliability of important components are shown. The comparative graph of reliability is also given to easily compare the reliability of each sub components.
Conclusion: In this research paper a newer technique is used to calculate the time based reliability of evaporator used in domestic refrigerator. This method of calculation is also applicable for all types of dynamic system. The reliability of evaporator appears almost 95.45% at the end of fifteenth year.
Keywords: Evaporator, Reliability, Refrigerant, Domestic refrigerator, Dynamic system
Full Text:
Evaporator is that component of refrigerator in which actual purpose of refrigeration of commodity is fulfilled. It the part from where the actual performance of refrigeration system can also be calculated.[1],[7]
In general the evaporator used in domestic refrigerator is also known as freezer. The refrigerant flowing in the system enters in evaporator in liquid state and leaves in gaseous or vapor state. To achieve higher heat exchanging response and low material cost the evaporator is built by aluminum metal.[5]
Here the data used for reliability calculation of evaporator is collected from a certified refrigeration sales and servicing agency named as Chandra Sales which is providing its technical solution and services since last eighteen years. The data picked contains the record of 216 domestic refrigerators in which the servicing details of the evaporators and related components are given[8]. Here from the observation of log book it is clear that the reliability of evaporator is largely affected by choking or blockage of evaporative coil and leakage of refrigerant.[3,4]
MATERIALS AND METHODS
Data Collection and Measurement: The reliability measurement technique is totally based on the data collected. The collected data provide the average failure rate for system dynamic modeling on Vensim-PLE software.
In modeling the reliability of various components of evaporator is considered as decay in these components is exponentially with time. Since all components are in different working condition, but the components considered above are most important and directly affect the reliability and performance of the evaporator.
System Dynamic Modeling of Evaporator
Reliability of Evaporator : ROE
Leakage of Refrigerant : LOR
Choking/ Blockage in evaporative coil
: CEC
Fig-1 : Showing the system modeling of evaporator used in VCRS
Programming Details
. (1) CEC= EXP(-0.0015*Time)
Units: RELIABILITY
(2) FINAL TIME = 15
Units: Year
The final time for the simulation.
(3) INITIAL TIME = 0
Units: Year
The initial time for the simulation.
(4) LOR= EXP(-0.0016*Time)
Units: RELIABILITY
(5) ROE= CEC*LOR
Units: RELIABILITY
(6) SAVEPER = TIME STEP
Units: Year [0,?]
The frequency with which output is stored.
(7) TIME STEP = 1
Units: Year [0,?]
The time step for the simulation.
RESULT
Graphical Outputs for Evaporator: Fig-2: Comparative reliability graphs showing reliability from 0 to 15 years Output Table: Table -2
From the above data it is confirmed that choking in evaporative coil is important parameter that considerably affects the
reliability of evaporator. During modification in the functioning of evaporator we must concentrate towards the rectification regarding choking of evaporative coil. From the observation table it is found that at the end of fifteenth year the reliability of choking coil falls to 97.77%. The reliability parameter like leakage of refrigerant falls to 97.62% at the end of fifteenth years which also affect the performance of evaporator.
DISCUSSION
Domestic refrigerator has four important components like evaporator, compressor, condenser and expansion devices like capillary tubes with filter drier. The reliability of overall vapour compression refrigeration system like domestic refrigerator can be calculated by calculating the reliabilities of above components separately.
CONCLUSION
Overall reliability of evaporator decreases from 100% to 95.45% at the end of fifteenth year from starting. This percentage is not feasible for confident running of vapor compression refrigeration system for fifteen years. Hence at this stage of design modification is necessary.
ACKNOWLEDGEMENT
Authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.
Authors are also thankful to Teerthankar Mahaveer University Moradabad for providing us a good research atmosphere and valuable guidance to complete our research work. We are also thankful to the refrigeration servicing agency for providing us the valuable data regarding the problems of maintenance of evaporators used in domestic refrigerators.
References:
- Evaporator:http://www.airconditioning-systems.com/evaporator.html
: access on 02.02.2017
- From Wikipedia, the free encyclopedia :”https://en.wikipedia.org/wiki/Evaporator : access on 05.12.16
- Fennema, Owen R., Marcus Karel, and Daryl B. Lund. Physical Principles of Food Preservation. Marcel Deker, Inc. New York and Basel, 1975.
- http://absorptionchiller4u.blogspot.com/2013/01/evaporator-types-of-evaporators.html : 0n 11.09.16
- www.actrol.com.au/Showcase/Refrigeration-Evaporators/ access 0n 04.12.15
- nptel.ac.in/courses/112105129/pdf/R&AC%20Lecture%2023.pdf : access 0n 02.12.16
- www.probrewer.com › Library › Refrigeration : access 0n 09.02.17
- Handbook on Handbook of Research on Advances and Applications in Refrigeration , page 696 . 2013
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