Charge Optimization in Window Air Conditioner with Commercial LPG (Hydrocarbon Blend)

In this paper, the window air conditioner performance with commercial LPG as a replacement of HFC134a is assessed with modified capillary lengths for charge optimization. Global Warming Potential (GWP) of commercial LPG is only three, which is neglected compared to HFC134a (1300). Flammability issues will also be reduced in charge optimization and adopting safety standards. Initially, baseline tests are conducted with HFC134a and commercial LPG in the existing system, and optimum refrigerant charge is determined. The simulation study is conducted with modified capillary lengths for charge reduction of commercial LPG. Experimental assessment is conducted for the charge optimization as per IS 1349 (Part 1) for low ambient test conditions (Domestic Test-DT and Export Test A-ETA) and high ambient test conditions (Export Test B-ETB). With the optimized capillary length and optimum charge quantity, 0.4–2.03% higher cooling capacity, 0.62–8.9% lesser power consumption, and 10.49–16.4% higher COP are achieved with commercial LPG than that of HFC134a baseline at low and high ambient test conditions, respectively.

Semiconducting properties of pyridyl appended linear dicarboxylate based coordination polymers: theoretical prediction via DFT study

This work highlights the theoretical elucidation of semiconducting properties and a probable pathway for the optimum charge transportation in coordination polymers.

Chemical Insights into Electrophilic Fluorination of Tin Oxide Layer for Photoelectrochemical Applications

Recently, there has been substantial interest in the fluorination of nanomaterial thin films used in various optoelectronic devices for optimum charge transport across semiconducting layers. The discovery of electrophilic fluorinating...

Charge optimisation of a solar milk chiller with direct current compressors

In view of promoting the utilization of solar photo-voltaic energy for milk chilling application a custom designed milk chiller with DC compressors was fabricated. Two different DC compressors were used operating with HFC-134a and HC-600a refrigerants to ascertain the performance of HFC and HC refrigerants when used in solar powered application. In view of optimizing the performance of both refrigerants, charge optimization was experimentally carried out for both refrigerant circuits. The optimum charge was obtained based on the maximum coefficient of performance and exergy efficiency. When comparing ice formation and coefficient of performance, the HC-600a refrigerant circuit was lower than that of HFC-134a circuit. It was also observed that the total exergy destruction experienced was maximum in the HFC-134a circuit than that of the HC-600a circuit. The magnitude of exergy destruction was found to be maximum in the compressor and then followed by the condenser, evaporator and finally the capillary for both refrigeration circuits. This study showed an efficient way for using the solar power for operating a milk chiller with DC compressors and with ice bank tank to avoid the dependency on batteries.

Influence of Seismic Source Parameters on the Excitation Wavelet in Seismic Explorations Based on Numerical Simulation

Explosives are the most common seismic source in seismic explorations, whose excitation effect is closely associated with their properties, weight, buried depth, and charging constitution. This study analyzes the influence of seismic source parameters on the features of the explosion wavelet. The explosion process of the seismic source in marine carbonate is numerically simulated with the finite element software LS-DYNA. We consider three parameters, including buried depth, charge weight, and decoupling coefficient. To verify the simulation outcomes, we also carry out field observations. The appropriate buried depth of the explosive should be determined according to stratum lithology. As the charge weight increases, low-frequency energy of the source wavelet increases rapidly. The optimum charge weight is 16–18 kg, and the ideal charging structure is in a concentrated, short-column shape. Compared with the buried depth and charge weight, the decoupling coefficient shows more noticeable influence on the excitation effect of the source wavelet, and the optimum coefficient lies between 2.5 and 3. The results of this study may provide reference data for designing explosion parameters in field seismic explorations.

A Novel Hybrid Deep Neural Network Model to Predict the Refrigerant Charge Amount of Heat Pumps

Improper refrigerant charge amount (RCA) is a recurring fault in electric heat pump (EHP) systems. Because EHP systems show their best performance at optimum charge, predicting the RCA is important. There has been considerable development of data-driven techniques for predicting RCA; however, the current data-driven approaches for estimating RCA suffer from poor generalization and overfitting. This study presents a hybrid deep neural network (DNN) model that combines both a basic DNN model and a thermodynamic model to counter the abovementioned challenges of existing data-driven approaches. The data for designing models were collected from two EHP systems with different specifications, which were used for the training and testing of models. In addition to the data obtained using the basic DNN model, the hybrid DNN model uses the thermodynamic properties as a thermodynamic model. The testing results show that the hybrid DNN model has a prediction performance of 93%, which is 21% higher than that of the basic DNN model. Furthermore, for model training and model testing, the hybrid DNN model has a 6% prediction performance difference, indicating its reliable generalization capabilities. To summarize, the hybrid DNN model improves data-driven approaches and can be used for designing efficient and energy-saving EHP systems.

Burden Optimisation of Lump Charge Materials for Foundry Furnaces

Calculation of economically optimum charge burden for foundry furnaces depends on a solution that can be found in the field of mathematical linear programming. A traditional linear optimisation method means looking for continuous variables that can define portion of every charge component.Sometimes, it can be observed that a calculated portion of charge material with a defined lump mass is rounded up, which is wrong because the charge burden prepared in such a way may either show a mistaken chemical composition, or it can entail a significant cost. With charge materials characterised by defined mass lumps, it is recommended to use a modified method of integer linear optimisation.This article contains definitions of a goal function and a system of constraints considering the charge materials as stated above. In addition, a sample calculation has been included hereto to show such optimisation for a selected process of metal melting in a casting furnace.

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

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.