Optimization of the Water Spray Nozzle, Refrigerant Charge Amount and Expansion Valve Opening for a Unitary Ice Maker Using R-404A

2017 ◽  
Vol 25 (03) ◽  
pp. 1750025 ◽  
Author(s):  
Nae-Hyun Kim
Keyword(s):  
Ozone Depletion ◽  
Heat Transfer Performance ◽  
Condensation Temperature ◽  
Refrigeration Cycle ◽  
Evaporation And Condensation ◽  
Start Up ◽  
Expansion Valve ◽  
Valve Opening ◽  
Ice Production ◽  
Optimum Charge

R-502, which had long been used as the refrigerant of a unitary ice maker, has been replaced by R-404A due to ozone depletion. In this study, the refrigeration cycle of a unitary ice maker was optimized using R-404A. The optimization was accomplished through a search for the proper refrigerant charge amount and the opening of the expansion valve. For the present ice maker having 24 ice cups, the optimum charge amount was 580[Formula: see text]g and the optimum valve opening was “0”. At this configuration, the ice making time was 12[Formula: see text]min 55[Formula: see text]sec, ice production was 4.46[Formula: see text]kg/h and COP was 0.439. After the initial start-up period, both condensation and evaporation temperature gradually decrease with time. As ice builds up in the cup, the heat transfer performance of the evaporator decreases, which results in the decrease of the evaporation and condensation temperature. Through CFD and relevant experiments, optimum nozzle slit width and nozzle to cup distance were obtained.

Application of the Natural Refrigerant Mixture R-290/DME to a Soft Ice Cream Refrigerator

2016 ◽  
Vol 24 (04) ◽  
pp. 1650027 ◽  
Author(s):  
Nae-Hyun Kim
Keyword(s):  
Ozone Depletion ◽  
Ice Cream ◽  
Formation Time ◽  
Actual Usage ◽  
Refrigerant Mixture ◽  
Expansion Valve ◽  
Valve Opening ◽  
Natural Refrigerant ◽  
Optimum Charge

Due to the ozone depletion issue, R-502, which had long been used as the refrigerant of an ice cream refrigerator, has been replaced by R-404A. However, global warming potential (GWP) of R-404A is high, and thus, a replacement refrigerant is necessary in the long term. Natural refrigerants, such as R-290 or DME (dimethylether), could be a choice. In this study, an ice cream refrigerator cycle was optimized using R-290/DME mixture (mass fraction 65/35). The optimization was accomplished through a search for the proper refrigerant charge amount and the opening of the expansion valve. For the present ice cream refrigerator having 2.8[Formula: see text]L freezer volume, the optimum charge amount was 900[Formula: see text]g, and the optimum valve opening was [Formula: see text]120[Formula: see text]. At this configuration, the ice cream formation time was 3[Formula: see text] 6[Formula: see text] and COP was 2.0. The ice cream formation time was much shorter than when R-404A was used, and the COP was increased by more than 100%. For actual usage of the refrigerant, however, the flammability issue of the R-290/DME mixture should be cleared.

Dynamic Modelling and Experimental Validation of a Domestic Refrigeration Cycle

2021 ◽  
pp. 1-33
Author(s):  
Akin Caglayan ◽  
Salman Mustafa Husain ◽  
Mutlu Ipek ◽  
Tolga Nurettin Aynur ◽  
Sertac Cadirci
Keyword(s):  
Capillary Tube ◽  
Dynamic Modelling ◽  
Object Oriented Programming ◽  
Condensation Temperature ◽  
Refrigeration Cycle ◽  
Transient Behaviour ◽  
Analysis And Design ◽  
Cyclic Behaviour ◽  
Suction Line Heat Exchanger ◽  
Tube Suction

Abstract Performance analysis and design optimization of refrigerators are primarily carried out by time-consuming experiments. The current study presents an alternative method of analysing refrigerators through modelling of the cooling cycle using a software called Dymola, based on an object-oriented programming language, called Modelica. The main components of a domestic refrigerator (compressor, condenser, evaporator, cabinet and capillary tube-suction-line heat exchanger) are first modelled and validated individually. The full dynamic refrigeration cycle model is created afterwards. Both the simulations and the experiments have been conducted using R600a as the refrigerant with on-and off-modes of the reciprocating, single speed compressor. To represent the dynamic cyclic behaviour of the refrigerator, an algorithm block is also included. The algorithm controls the operation using two set-point temperatures of the cabinet. Experiments have been carried out on a single door refrigerator having an interior volume of 343 litres for the validation of the one-dimensional dynamic model. Results show that the cabinet air, evaporation temperature, condensation temperature, power and energy values deviate from experimental values by less than 2°C and 2% respectively. The dynamic modelling is found to be in good agreement with the experiments in the on mode of the compressor and a promising and rapid tool to represent the transient behaviour of the refrigerator.

scholarly journals Efficiency Evaluation of the Ejector Cooling Cycle using a New Generation of HFO/HCFO Refrigerant as a R134a Replacement

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2136 ◽  
Author(s):  
Bartosz Gil ◽  
Jacek Kasperski
Keyword(s):  
High Efficiency ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Evaporation And Condensation ◽  
Wide Range ◽  
Theoretical Investigations ◽  
Maximum Coefficient ◽  
C 30 ◽  
New Generation ◽  
And Control

Theoretical investigations of the ejector refrigeration system using hydrofluoroolefins (HFOs) and hydrochlorofluoroolefin (HCFO) refrigerants are presented and discussed. A comparative study for eight olefins and R134a as the reference fluid was made on the basis of a one-dimensional model. To facilitate and extend the possibility of comparing our results, three different levels of evaporation and condensation temperature were adopted. The generator temperature for each refrigerant was changed in the range from 60 °C to the critical temperature for a given substance. The performed analysis shown that hydrofluoroolefins obtain a high efficiency of the ejector system at low primary vapor temperatures. For the three analyzed sets of evaporation and condensation temperatures (te and tc equal to 0 °C/25 °C, 6 °C/30 °C, and 9 °C/40 °C) the maximum Coefficient of Performance (COP) was 0.35, 0.365, and 0.22, respectively. The best performance was received for HFO-1243zf and HFO-1234ze(E). However, they do not allow operation in a wide range of generator temperatures, and, therefore, it is necessary to correctly select and control the operating parameters of the ejector.

Research on Electronic Expansion Valve Opening Mechanical Properties of Multi-Link Inverter Air-Con Based on Neural Network

2013 ◽  
Vol 644 ◽  
pp. 64-67
Author(s):  
Li Hui Guo ◽  
Wan Qiang Hu
Keyword(s):  
Neural Network ◽  
Mechanical Properties ◽  
Pid Controller ◽  
Control Mode ◽  
Expansion Valve ◽  
Valve Opening

The effects are unsatisfactory to adopt plain control mode for air-con refrigerating system with large lagging and nonlinearit features. The mechanical properties of electronic expansion valve are not sensible. In this article, BP-PID controller is adopted to control the system’s electronic expansion valve opening mechanical properties. The controller is designed. The experiment results show the controller is simple and effective, and well fulfills the users’ actual needs.

scholarly journals Experimental Study on the Evaporation and Condensation Heat Transfer Characteristics of a Vapor Chamber

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 11
Author(s):  
Yanfei Liu ◽  
Xiaotian Han ◽  
Chaoqun Shen ◽  
Feng Yao ◽  
Mengchen Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Condensation Heat Transfer ◽  
Transfer Performance ◽  
Vapor Chamber ◽  
Filling Rate ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Evaporation And Condensation

A vapor chamber can meet the cooling requirements of high heat flux electronic equipment. In this paper, based on a proposed vapor chamber with a side window, a vapor chamber experimental system was designed to visually study its evaporation and condensation heat transfer performance. Using infrared thermal imaging technology, the temperature distribution and the vapor–liquid two-phase interface evolution inside the cavity were experimentally observed. Furthermore, the evaporation and condensation heat transfer coefficients were obtained according to the measured temperature of the liquid near the evaporator surface and the vapor near the condenser surface. The effects of heat load and filling rate on the thermal resistance and the evaporation and condensation heat transfer coefficients are analyzed and discussed. The results indicate that the liquid filling rate that maximized the evaporation heat transfer coefficient was different from the liquid filling rate that maximized the condensation heat transfer coefficient. The vapor chamber showed good heat transfer performance with a liquid filling rate of 33%. According to the infrared thermal images, it was observed that the evaporation/boiling heat transfer could be strengthened by the interference of easily broken bubbles and boiling liquid. When the heat input increased, the uniformity of temperature distribution was improved due to the intensified heat transfer on the evaporator surface.

Experimental analysis of the low-GWP refrigerant R1234yf as a drop-in replacement for R134a in a typical mobile air conditioning system

2012 ◽  
Vol 226 (11) ◽  
pp. 2713-2725 ◽  
Author(s):  
Yu Zhao ◽  
Zhaogang Qi ◽  
Jiangping Chen ◽  
Baixing Xu ◽  
Bin He
Keyword(s):  
Working Conditions ◽  
Air Conditioning ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Laminated Plate ◽  
Improve Performance ◽  
Air Conditioning System ◽  
Expansion Valve ◽  
Variable Displacement ◽  
Valve Opening

This study investigated the performance of a typical mobile air conditioning system using R134a and R1234yf as the working fluids under different working conditions. The system is composed of a microchannel parallel flow condenser, a laminated plate evaporator, a variable displacement compressor, and a thermal expansion valve. The different working cycles of each refrigerant were comprehensively compared. The optimum refrigerant charge amount of the R1234yf system was approximately 95% of the R134a system during drop-in tests. The performance of the R134a system was a little higher than that of the R1234yf system. The cooling capacity and system coefficient of performance of the R134a system were 12.4% and 9% larger, respectively. This result is mainly because of the thermophysical property differences between the two refrigerants and the improper expansion valve opening of R1234yf. Analysis on the whole cycle revealed that the R1234yf system could obtain a higher evaporating pressure and a larger superheat and subcooling. Redesigning the expansion valve for R1234yf could improve performance of the system.

scholarly journals Refrigerant Charge Prediction of Vapor Compression Air Conditioner Based on Start-Up Characteristics

2021 ◽  
Vol 11 (4) ◽  
pp. 1780
Author(s):  
Yechan Yun ◽  
Young Soo Chang
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Test Data ◽  
Dynamic Characteristics ◽  
Dynamic Models ◽  
Prediction Models ◽  
Support Vector ◽  
Condensation Temperature ◽  
Discharge Temperature ◽  
Start Up

Refrigerant charge faults, which occur frequently, increase the energy loss and may fatally damage the system. Refrigerant leakage is difficult to detect and diagnose until the fault has reached a severe degree. Various techniques have been developed to predict the refrigerant charge amount based on steady-state operation; however, steady-state experiments used to develop prediction models for the refrigerant charge amount are expensive and time-consuming. In this study, a prediction model was established with dynamic experimental data to overcome these deficiencies. The dynamic models for the condensation temperature, degree of subcooling, compressor discharge temperature, and power consumption were developed with a regression support vector machine (r-SVM) model and start-up experimental data. The dynamic models for the condensation temperature and degree of subcooling can predict the distinct start-up characteristics depending on the refrigerant charge amount. Moreover, the estimated root mean square error (RMSE) of the condensation temperature and degree of subcooling of the test data are 0.53 and 0.84 °C, respectively. The refrigerant charge is one of the predictors that defines the dynamic characteristics. The refrigerant charge can be estimated by minimizing the RMSE of the predicted values of the dynamic models and experimental data. When the dynamic characteristics of the two predictor variables, “condensation temperature” and “degree of subcooling” are used together, the average prediction error of the test data is 2.54%. The proposed method, which uses the dynamic model during start-up operation, is an effective technique for predicting the refrigerant charge amount.

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