scholarly journals ANN Modeling to Analyze the R404A Replacement with the Low GWP Alternative R449A in an Indirect Supermarket Refrigeration System

2021 ◽  
Vol 11 (23) ◽  
pp. 11333
Author(s):  
Morteza Ghanbarpour ◽  
Adrián Mota-Babiloni ◽  
Pavel Makhnatch ◽  
Bassam E. Badran ◽  
Jörgen Rogstam ◽  
...  
Keyword(s):  
Measurement Data ◽  
Field Measurements ◽  
Energy Performance ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Refrigeration System ◽  
Ann Model ◽  
Ann Modeling ◽  
Temperature Levels ◽  
Variable Operating Conditions

Artificial neural networks (ANNs) have been considered for assessing the potential of low GWP refrigerants in experimental setups. In this study, the capability of using R449A as a lower GWP replacement of R404A in different temperature levels of a supermarket refrigeration system is investigated through an ANN model trained using field measurements as input. The supermarket refrigeration was composed of two indirect expansion circuits operated at low and medium temperatures and external subcooling. The results predicted that R449A provides, on average, a higher 10% and 5% COP than R404A at low and medium temperatures, respectively. Moreover, the cooling capacity was almost similar with both refrigerants in both circuits. This study also revealed that the ANN model could be employed to accurately predict the energy performance of a commercial refrigeration system and provide a reasonable judgment about the capability of the alternative refrigerant to be retrofitted in the system. This is very important, especially when the measurement data comes from field measurements, in which values are obtained under variable operating conditions. Finally, the ANN results were used to compare the carbon footprint for both refrigerants. It was confirmed that this refrigerant replacement could reduce the emissions of supermarket refrigeration systems.

Performance Analysis on a Solar-Driven Air-Cooled Ejector Refrigeration System for Air-Conditioning Using Ammonia as Refrigerant

2014 ◽  
Vol 501-504 ◽  
pp. 2282-2287 ◽  
Author(s):  
Yu Hang Liao ◽  
Wei Lu ◽  
Lie Pan
Keyword(s):  
Performance Analysis ◽  
Solar Irradiance ◽  
Air Conditioning ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Refrigeration System ◽  
Outdoor Temperature ◽  
Indoor Temperature ◽  
Changing Trend

The performance of a solar-driven air-cooled ejector refrigeration system using ammonia as refrigerant with rated cooling capacity of 10.5kW was analyzed for air-conditioning purpose. The cooling capacity of the proposed system increases with the rising of indoor temperature and enhancement of solar irradiance, while decreases with the rising of outdoor temperature. The COP has similar changing trend with that of the cooling capacity except that it increases rapidly with the enhancement of solar irradiance firstlyand then become stable by and large after solar irradiance exceeding a certain value. The cooling capacity is 6.3~52kW and the COP 0.06~0.11 under the normal operating conditions with indoor temperature over 27, outdoor temperature below 38°C and solar irradiance surpassing 500 W/m2. The proposed system can match the climatic conditions in air-conditioning season of Nanning, a typical city in hot summer and warm winter region.

scholarly journals Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5991
Author(s):  
Christian J. L. Hermes ◽  
Joel Boeng ◽  
Diogo L. da Silva ◽  
Fernando T. Knabben ◽  
Andrew D. Sommers
Keyword(s):  
First Principles ◽  
Simulation Models ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Trial And Error ◽  
Refrigeration System ◽  
Duty Cycles ◽  
Transfer Principles ◽  
Frost Layer

Modern refrigerators are equipped with fan-supplied evaporators often tailor-made to mitigate the impacts of frost accretion, not only in terms of frost blocking, which depletes the cooling capacity and therefore the refrigerator coefficient of performance (COP), but also to allow optimal defrosting, thereby avoiding the undesired consequences of condensate retention and additional thermal loads. Evaporator design for frosting conditions can be done either empirically through trial-and-error approaches or using simulation models suitable to predict the distribution of the frost mass along the finned coil. Albeit the former is mandatory for robustness verification prior to product approval, it has been advocated that the latter speeds up the design process and reduces the costs of the engineering undertaking. Therefore, this article is aimed at summarizing the required foundations for the design of efficient evaporators and defrosting systems with minimized performance impacts due to frosting. The thermodynamics, and the heat and mass transfer principles involved in the frost nucleation, growth, and densification phenomena are presented. The thermophysical properties of frost, such as density and thermal conductivity, are discussed, and their relationship with refrigeration operating conditions are established. A first-principles model is presented to predict the growth of the frost layer on the evaporator surface as a function of geometric and operating conditions. The relation between the microscopic properties of frost and their macroscopic effects on the evaporator thermo-hydraulic performance is established and confirmed with experimental evidence. Furthermore, different defrost strategies are compared, and the concept of optimal defrost is formulated. Finally, the results are used to analyze the efficiency of the defrost operation based on the net cooling capacity of the refrigeration system for different duty cycles and evaporator geometries.

Effect of Hydrofluorocarbons and Hydrofluoroolefins in a Household Refrigerator as a Substitute for R134a

2019 ◽  
Vol 969 ◽  
pp. 199-204
Author(s):  
Shaik Mohammad Hasheer ◽  
Kolla Srinivas
Keyword(s):  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Outlet Temperature ◽  
Refrigeration System ◽  
Volumetric Cooling ◽  
Work Done ◽  
Theoretical Results ◽  
Hfc 152A

Now a days R134a can be used in domestic refrigerators and in air conditioning of automobiles. As per Kyoto protocol the usage of R134a is restricted due to their higher GWP value. The GWP value of this refrigerant is around 1430. So in this article, thermodynamic analysis of HFC-152a, HFO refrigerants-1234ze(E) and 1234yf was done in a household refrigeration system as direct substitute to HFC-134a.The performance of the household refrigerator was compared in terms of outlet temperature of the compressor, volumetric cooling capacity (VCC), refrigeration effect, work done by the compressor and coefficient of performance (COP). The entire analysis is carried out at various operating conditions of condenser and evaporator temperatures i.e. condensation temperature of 25°C,35°C & 45°C and evaporating temperatures ranging between −20°C to 10°C.From the theoretical results, it can be concluded that R1234yf can be used as a direct substitute to R134a.

Design and Evaluation of MEMS-Based Stirling Cycle Micro-Refrigeration System

2011 ◽  
Author(s):  
Dongzhi Guo ◽  
Jingsheng Gao ◽  
Alan J. H. McGaughey ◽  
Matthew Moran ◽  
Suresh Santhanam ◽  
...  
Keyword(s):  
Volume Ratio ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Heat Extraction ◽  
Dead Volume ◽  
Working Fluid ◽  
Phase Lag ◽  
Refrigeration System ◽  
Cold Side ◽  
Stirling Cycle

A Stirling cycle micro-refrigeration system composed of arrays of silicon MEMS cooling elements has been designed and evaluated thermodynamically. The cooling elements are each 5 mm-long, 2.25 mm-wide, have a thickness of 300 μm, and are fabricated in a stacked array on a silicon wafer. A 0.5 mm-long regenerator is placed between the compression (hot side) and expansion (cold side) diaphragms. The diaphragms are 2.25 mm circles driven electrostatically. Helium is the working fluid, pressurized at 2 bar and sealed in the system. Under operating conditions, the hot and cold diaphragms oscillate sinusoidally 90° out of phase such that heat is extracted to the expansion space and released from the compression space. The bulk silicon substrate on which the device is grown is etched with “zipping” shaped chambers under the diaphragms. The silicon enables efficient heat transfer between the gas and heat source/sink as well as reduces the dead volume of the system, thus enhancing the cooling capacity. In addition, the “zipping” shaped substrates reduce the voltage required to actuate the diaphragms. An array of vertical silicon pillars in the regenerator serves as a thermal capacitor transferring heat to and from the working gas during a cycle. In operation, the push-pull motion of the diaphragm makes a 300 μm stroke and actuates at a frequency of 2 kHz. Parametric study of the design shows the effects of phase lag, swept volume ratio between the hot space and cold space, and dead volume ratio on cooling capacity. At TH = 313.15 K and TC = 288.15 K and assuming a perfect regenerator, the thermodynamic optimization analysis gives a heat extraction rate of 0.22 W per element and cooling capacity of 30 W/cm2 for the stacked system. Evaluation of the stacked system shows that the COP will reach 6.3 if the expansion work from the cold side is recovered electrostatically and used to drive the hot side diaphragm.

FUZZY-PID CONTROLLER APPLIED TO A REFRIGERATION SYSTEM

2012 ◽  
Vol 20 (02) ◽  
pp. 1250006 ◽  
Author(s):  
JONES ERNI SCHMITZ ◽  
FLAVIO VASCONCELOS DA SILVA ◽  
ANA MARIA FRATTINI FILETI ◽  
LINCOLN CAMARGO NEVES FILHO ◽  
VIVALDO SILVEIRA JÚNIOR
Keyword(s):  
Expert Knowledge ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Pid Controllers ◽  
Fuzzy Pid ◽  
Refrigeration System ◽  
Experimental Development ◽  
Fuzzy Controllers ◽  
Fuzzy Pid Controller ◽  
Complex Methods

A refrigeration system exhibits a dynamic behavior on which the variables are interdependent and subjected to oscillation, hence, implicating necessity of changes on operating conditions and undesirable energy expenses. These characteristics ratify the importance of adequate dimensioning and equipment selection to find pre-defined operating conditions such as, the maximum cooling capacity and the evaporating and condensing temperatures. The application of fuzzy control in industrial processes is growing fast in the last decades, mainly in processes whose first principle models require complex methods to be simulated. In these cases, the fuzzy controllers’ capacity of acting correctly based only on expert knowledge and on the capacity of inter-relating all the variables of the process are attractive features. This work presents the experimental development and evaluation of fuzzy-PID controllers for the maintenance of the evaporating temperature in a chiller. The system was submitted to load and set-point disturbances accomplishing an analysis based upon error parameters and transient response. The results showed that fuzzy controllers were adapted satisfactorily.

Analysis of Heat-Driven Combined Cooling and Desalination

2016 ◽  
Author(s):  
Sami M. Alelyani ◽  
Nicholas W. Fette ◽  
Ellen B. Stechel ◽  
Pinchas Doron ◽  
Patrick E. Phelan
Keyword(s):  
Second Law Of Thermodynamics ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Water Production ◽  
Exergy Destruction ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Cooling Systems ◽  
Thermally Driven ◽  
Combined Cooling

This paper investigates the opportunities for integrating thermally driven cooling systems with thermally driven desalination systems via cascade of reject heat. Single- and double-stage ammonia-water (NH3–H2O) absorption refrigeration systems with multi-effect distillation (MED) are selected for this study based on technical limitations and practical considerations. Cooling capacity and hourly water production are calculated from thermodynamic properties of the working fluids at different operating conditions using simple models for each of the constituent systems. Additionally, the second law of thermodynamics is applied with the aim of examining the entropy generation of each component as well as the total exergy destruction of the entire system. The results indicate that the total exergy destruction of the combined systems, which consist of an MED unit driven by either a single- or double-stage NH3–H2O refrigeration system, decreases by an average of 55% compared to stand-alone NH3–H2O and MED systems. Relative to stand-alone systems, although water production decreases by 30% and 9% when an MED unit is integrated with single- and double-stage NH3–H2O absorption systems, respectively, cooling capacity remains unchanged for the double-stage NH3-H2O–MED system, and only decreases by 16% for the single-stage NH3-H2O–MED system.

scholarly journals Investigation on the Performance of a Solar Hybrid Refrigeration System Using Environmentally Friendly Fluids

2020 ◽  
Vol 38 (4) ◽  
pp. 960-966
Author(s):  
Latra Boumaraf ◽  
Rachedi Khadraoui
Keyword(s):  
Cooling Capacity ◽  
Operating Conditions ◽  
Mechanical Compression ◽  
Refrigeration System ◽  
Perfect Gas ◽  
Entrainment Ratio ◽  
Medium Temperature ◽  
D Model ◽  
Constant Section ◽  
Solar Refrigeration

In order to evaluate the performance of a hybrid compression / ejection refrigeration system using solar energy at low or medium temperature, a simulation model of its behavior based on those of its various components has been developed. It includes in particular for the ejector, a 1-D model of the "constant section mixing" type developed in optimal transition regime. The refrigerants tested are steam for the ejector loop and the R1234yf (replacing the R134a) for the mechanical compression loop. The behavior of the H2O vapor flowing in the ejector is considered that of the perfect gas. The properties of refrigerants are calculated using REFPROP® software, everywhere else. For a cooling capacity of 10 kW and air conditioning operating conditions, the model allows to determine the main parameters of the ejector and its entrainment ratio, the thermal and mechanical COP of the whole refrigeration system as well as the necessary surface of the solar collector. Furthermore, the influence of the temperature of the boiler, the condenser, the intercooler as well as that of the evaporator on the mechanical COP of the hybrid system and the solar collection surface in particular, were examined. The results highlight that the solar refrigeration system with hybrid cycle compression/ejection using the refrigerants H2O/R1234yf allows an increase of the mechanical COP higher than 50% compared to that of the conventional refrigeration system and thus constitutes an acceptable ecologically system that can compete with the latter.

Exergy and Cost Optimization of a Two-Stage Refrigeration System Using Refrigerant R32 and R410A

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Ranendra Roy ◽  
Arup Jyoti Bhowal ◽  
Bijan Kumar Mandal
Keyword(s):  
Cost Optimization ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Refrigeration System ◽  
Environmental Aspects ◽  
Two Stage ◽  
Cost Rate ◽  
Discharge Temperature ◽  
Condenser Temperature

Abstract An attempt has been made to investigate numerically a two-stage refrigeration system with flash intercooler of 50 kW cooling capacity using refrigerant R410A and its possible alternative R32. Development of the simulation model for the analysis of the system has been carried out in engineering equation solver considering the energetic, exergetic, economic, and environmental aspects. Evaporator and condenser temperatures have been varied from −50 °C to −25 °C and 40 °C to 55 °C, respectively, to carry out the simulation work. Co-efficient of performance (COP), exergetic efficiency, and plant cost rate are the three performance parameters computed in this present work. Results show that the performances of the system using R32 are comparable with those of the system using R410A. It is also observed that R32 shows slightly better thermo-economic performances at higher condenser temperature. Multi-objective optimization has also been carried out using the toolbox available for optimization in matlab to obtain the optimum performance and optimum operating conditions for both the refrigerants. Optimization results also show better thermo-economic performances of R32 over R410A though compressor discharge temperature is higher in case of R32.

scholarly journals Design and Fabrication of Solar Powered Vapour Absorption Refrigeration System

2020 ◽  
Vol 170 ◽  
pp. 02011
Author(s):  
Varun Yadav ◽  
Supradeepa Panual G ◽  
Neeraj Yadav ◽  
Ratnam Bordia ◽  
Rohini Soni ◽  
...  
Keyword(s):  
Solar Energy ◽  
Cooling System ◽  
Energy Performance ◽  
Operating Conditions ◽  
Air Conditioner ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Evaporator Temperature ◽  
Absorption Refrigeration System ◽  
Solar Powered

Engineering is all about the application of knowledge and ideas for continuous development in society. In today’s world, there is a strong need for an environment-friendly refrigerating system, therefore, our focus is on a solar powered vapour absorption refrigeration system. This project focuses on a cooling system that minimizes the dependency over electricity and to show our ability to save our resources for future generations. The objective of this work was to design and fabricate a vapour absorption refrigeration system, using LiBr-H20, as the refrigerants and powered by solar energy. Performance Evaluation of the system has been done on the basis of different operating conditions and parameters like, solar irradiance, collector, generator, condenser and evaporator temperature. The COP of the system was obtained as 0.1 and the capacity was 0.01 TR. Since it’s an ab-initio development it will be a unique one in terms of understanding and underlying engineering. The system is an eccentric one that can be operated by multiple heat sources like solar energy, biomass etc. without much change in the design. This system can be used to develop an Air Conditioner, Refrigerator or a Chiller.

Investigations of Road Wear Caused by Studded Tires

2014 ◽  
Vol 42 (1) ◽  
pp. 2-15
Author(s):  
Johannes Gültlinger ◽  
Frank Gauterin ◽  
Christian Brandau ◽  
Jan Schlittenhard ◽  
Burkhard Wies
Keyword(s):  
Traffic Safety ◽  
Test Bench ◽  
Operating Conditions ◽  
Test Method ◽  
Analytical Models ◽  
The Road ◽  
Driving Speed ◽  
Major Factors ◽  
Tire Friction ◽  
Variable Operating Conditions

ABSTRACT The use of studded tires has been a subject of controversy from the time they came into market. While studded tires contribute to traffic safety under severe winter conditions by increasing tire friction on icy roads, they also cause damage to the road surface when running on bare roads. Consequently, one of the main challenges in studded tire development is to reduce road wear while still ensuring a good grip on ice. Therefore, a research project was initiated to gain understanding about the mechanisms and influencing parameters involved in road wear by studded tires. A test method using the institute's internal drum test bench was developed. Furthermore, mechanisms causing road wear by studded tires were derived from basic analytical models. These mechanisms were used to identify the main parameters influencing road wear by studded tires. Using experimental results obtained with the test method developed, the expected influences were verified. Vehicle driving speed and stud mass were found to be major factors influencing road wear. This can be explained by the stud impact as a dominant mechanism. By means of the test method presented, quantified and comparable data for road wear caused by studded tires under controllable conditions can be obtained. The mechanisms allow predicting the influence of tire construction and variable operating conditions on road wear.

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