scholarly journals Functional Equations for Calculating the Properties of Low-GWP R1234ze(E) Refrigerant

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3052
Author(s):  
Piotr Życzkowski ◽  
Marek Borowski ◽  
Rafał Łuczak ◽  
Zbigniew Kuczera ◽  
Bogusław Ptaszyński
Keyword(s):  
Functional Equations ◽  
Air Conditioning ◽  
Linear Least Squares ◽  
Legal Requirements ◽  
Relative Deviation ◽  
Small Deviations ◽  
Subcooled Liquid ◽  
Heating Systems ◽  
Marquardt Algorithm ◽  
Maximum Relative Deviation

Legal requirements for the use of refrigerants increasingly restrict the use of high-global warming potential (GWP) refrigerants. As a result, there is a growing interest in natural refrigerants and in those belonging to the hydrofluoroolefins (HFO) class, which can be used on their own or in mixtures. One of them is the R1234ze(E) refrigerant, an alternative to the R134a refrigerant as well as being a component of numerous mixtures. The knowledge of thermodynamic and transport properties of refrigerants is required for the analysis and calculation of refrigeration cycles in refrigeration, air conditioning, or heating systems. The paper presents analytical equations for calculating the properties of the R1234ze(E) refrigerant in the state of saturation and in the subcooled liquid and superheated vapour regions that do not require numerical calculations and are characterised by small deviations. The Levenberg–Marquardt algorithm—one of the methods for non-linear least squares estimation—was used to develop them. A total of 26 equations were formulated. The formulated equations were statistically verified by determining absolute and relative deviations between the values obtained from CoolProp software and calculated values. The maximum relative deviation was not higher than 1% in any of them.

Comparison on Simulation and Experiment of Supply Air through Metro Vehicle Air Conditioning Duct

2010 ◽  
Vol 44-47 ◽  
pp. 1724-1728
Author(s):  
Hong Ge Tao ◽  
Huan Xin Chen ◽  
Jun Long Xie ◽  
Jun Zhi Jiang
Keyword(s):  
Air Conditioning ◽  
Optimization Design ◽  
Simulation Method ◽  
Test Results ◽  
Air Velocity ◽  
Relative Deviation ◽  
Air Volume ◽  
Experiment Validation ◽  
Simulation And Experiment ◽  
Actual Test

CFD technique is often employed to simulate and optimize air duct design, but the corresponding experiment validation in metro vehicle is rare. By taking an independent metro vehicle duct as research object in this paper, supply air through air duct is simulated and compared with the actual test results from the angle of supply air velocity at each outlet and supply air volume through several outlets of air duct. The results show that the relative deviation of simulation and test value of air velocity at most of the outlets are within or near ±20%, which is acceptable for the engineering applications. Moreover, the ratio of supply air volume through several outlets to the corresponding total supply air volume through main air duct or flat duct in the case of simulation is consistent with that in the case of experiment. It can be concluded that numerical simulation method is effective and reliable in air duct optimization design of metro vehicle.

The Economic Performance of Ground-Source Heat Pumps

2014 ◽  
Vol 919-921 ◽  
pp. 1735-1738 ◽  
Author(s):  
Peng Gong ◽  
Jian Tang
Keyword(s):  
Energy Efficiency ◽  
Total Energy ◽  
Heat Pump ◽  
Air Conditioning ◽  
Ground Source Heat Pump ◽  
Ground Source Heat Pumps ◽  
Heating Systems ◽  
Ground Source ◽  
Groundwater Heat Pump ◽  
Central Air Conditioning

Ground-Source Heat Pump (PSHP) was verified by US Environmental Protection Agency (EPA) as one of the most efficient air conditioning systems on present market. It has a higher efficiency than other heating systems from 50% to 70%, and a higher efficiency than other cooling systems from 30% to 50%. The working principle of PSHP determines its low operating costs. By comparing the total energy efficiency, the existing groundwater heat pump total energy efficiency is the highest, about 115%. The total energy efficiency for soil-source heat pump is up to 100%. But traditional air conditioning is far less than the level. Articles present a research on Ground-Source Heat Pump system and its cost with a scientific and objective principles. Ground-source heat pump is a new central air conditioning system of Low-carbon energy saving. Due to the high technical content, function requirement, and installation difficulty , the average initial investment of ground-source heat pump is much higher than traditional central air conditioning. Taking into account the added costs of heating systems based on traditional central air-conditioning, such as boilers, it will not deviate too much from it.

scholarly journals Assessing the Environmental Impact of Thermal Transmittance Tests Performed in Façades of Existing Buildings: The Case of Spain

2020 ◽  
Vol 12 (15) ◽  
pp. 6247
Author(s):  
David Bienvenido-Huertas
Keyword(s):  
Energy Consumption ◽  
Environmental Impact ◽  
Thermal Gradient ◽  
Air Conditioning ◽  
Experimental Methods ◽  
Existing Buildings ◽  
Heating Systems ◽  
Thermal Transmittance ◽  
Test Conditions ◽  
Air Conditioning Systems

Thermal transmittance tests constitute an appropriate tool to assess the energy performance of existing buildings. The heat flow meter method and the thermometric method are the most used experimental methods. One of the main criteria to guarantee appropriate test conditions and the representation of results is to ensure a high thermal gradient. For this purpose, heating or air conditioning systems should be used from three to seven days. Most studies related to experimental methods have addressed the appropriate test conditions; however, the environmental impact related to these conditions have not been analyzed. This study analyzes the energy consumption and the CO2 emissions related to the conditions of the thermal gradient required for tests. An energy analysis of 129,600 cases located in Spain was conducted. The results showed that heating systems are the best option to perform thermal transmittance tests, whereas air conditioning systems do not guarantee appropriate test conditions. As for the energy consumption and the percentage of hours with an appropriate thermal gradient, the adequacy of the heating setpoint temperature according to the predicted estimations of the external temperature during tests would mitigate their environmental impact. The reason is that, in certain cases, the increase of the setpoint temperature does not improve test conditions. Also, the use of heating systems would imply short test durations. Finally, the selection of small rooms with a small façade length would reduce the percentage of CO2 emissions between 31.37% and 36.1%. The results of this study could guarantee a more sustainable performance of thermal transmittance tests. In addition, the results could be used to perform life cycle analysis on buildings where thermal transmittance tests are performed.

Economic Analysis of Solar Energy/Air Compound Source Heat Pump System

2011 ◽  
Vol 130-134 ◽  
pp. 1605-1608
Author(s):  
Tao Liu ◽  
Zhi Gang Zhang ◽  
Wei Zhang
Keyword(s):  
Solar Energy ◽  
Economic Analysis ◽  
Heat Pump ◽  
Air Conditioning ◽  
Evaluation Criteria ◽  
System Model ◽  
Pump System ◽  
Heat Pump System ◽  
Heating Systems ◽  
Air Source Heat Pump

The foundation, principle and prior condition and engineering economic Evaluation Criteria of engineering economic analysis are introduced. The economy for a solar energy/air source heat pump system is analyzed. Through a single air-cooled heat pump system, air conditioning in summer + winter heating systems, solar / air source compound heat pump system model analysis and comparison of three systems, integrated initial investment and running costs of both, come to solar / air source compound heat pump system has certain advantages in economical efficiency.

Expansion Tank Structural Reconstruction for Central Heating Systems With Re-Engineering Consideration and Energetic Losses Minimization

2015 ◽  
Author(s):  
Hamed Mohsenian ◽  
Hossein Ghadamian ◽  
Ali Asghar Hamidi ◽  
Karim Alizad
Keyword(s):  
Air Conditioning ◽  
Experimental Models ◽  
Efficient Design ◽  
Heating Systems ◽  
Central Heating ◽  
Proposed Model ◽  
Energy Auditing ◽  
Proper Design ◽  
Air Conditioning Systems ◽  
Energy Survey

Open expansion tanks are applied vastly in central heating and air-conditioning systems. Central heating systems are subjected to great deals of energy losses, owing to the lack of proper design. In this paper, the structure of Open Expansion Tanks is revised and some modifications for reducing energy and heat loss are made to their elements. Moreover, some common designs available in the market are studied in order to better recognize their defects and capabilities. To reach an efficient design, several scenarios are tested using Computational methods (CFD based). In order to validate the new design, an experimental model was created and heat and energy survey operations were performed. The results of energy auditing were analyzed to show the convergence of numerical and experimental models. Additionally, the proposed model was economically evaluated. The final presented model named “Optimized OET with twin containers” is capable of reducing the energy loss by 85 to 95 percent.

Neural network modeling as an efficient approach to predict the density of ionic liquids/ethanol binary systems

2017 ◽  
Vol 16 (04) ◽  
pp. 1750031 ◽  
Author(s):  
Mostafa Lashkarbolooki
Keyword(s):  
Neural Network ◽  
Ionic Liquids ◽  
Binary Data ◽  
Binary Systems ◽  
Statistical Error ◽  
Percentage Error ◽  
Neural Network Modeling ◽  
Ann Model ◽  
Relative Deviation ◽  
Maximum Relative Deviation

Ionic liquids (ILs) especially their mixtures are of high interest within the different scientific societies due to their amazing properties. In this regard, a number of attempts have been made to measure, correlate, estimate and calculate the properties of ILs in the neat or mixture forms. Among the different possible predictive methods, artificial neural networks (ANNs) are widely used because of their unique and amazing capabilities for prediction of different parameters. With respect to this paper, a feed-forward ANN model is proposed to model the densities of different binary mixtures of ILs/ethanol. The proposed network is trained and tested with 1078 binary data points gathered by mining into the different published literatures. The data gathered from previously published literatures are separated into two different subsets namely training and testing. The statistical error analysis has shown that the proposed neural network correlated the binary densities with the overall mean absolute percentage error (MAPE), average relative deviation percentage error (ARD%), minimum relative deviation percent (RDmin%), maximum relative deviation Percent (RDmax%) and correlation coefficient ([Formula: see text] of 1.5%, [Formula: see text]0.1%, [Formula: see text]13.0%, 15.0% and 0.9712, respectively.

Finite Element Simulation of Bending Stress on Involute Spur Gear Tooth Profiles

2017 ◽  
Vol 30 ◽  
pp. 1-10
Author(s):  
Kolawole Adesola Oladejo ◽  
Dare Aderibigbe Adetan ◽  
Ayobami Samuel Ajayi ◽  
Oluwasanmi Oluwagbenga Aderinola
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Gear Tooth ◽  
Spur Gear ◽  
Bending Stress ◽  
Relative Deviation ◽  
Element Simulation ◽  
Maximum Relative Deviation ◽  
Bending Stresses ◽  
Good Agreement

This study investigated bending stress distribution on involute spur gear tooth profiles with pressure angle of 20 ̊ but different modules 2.5, 4.0 and 6.0 mm, using a finite-element-based simulation package - AutoFEA JL Analyzer. The drafting of the geometry for the three gear tooth profiles were implemented on the platform of VB-AutoCAD customized environment, before importing to the package. These were separately subjected to analysis for bending stresses for a point at the tooth fillet region with appropriate settings of material property, load and boundary conditions. With the same settings, the bending stresses were computed analytically using American Gear Manufacturers Association (AGMA) established equation. The results of the two approaches were in good agreement, with maximum relative deviation of 4.38%. This informed the confidence in the implementation of the package to investigate the variation of bending stress within the gear tooth profile. The simulation revealed decrease in the bending stresses at the investigated regions with increase in the module of the involute spur-gear. The study confirms that Finite element simulation of stresses on gear tooth can be obtained accurately and quickly with the AutoFEA JL Analyzer.

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