Sensitivity of refrigeration system performance to charge levels and parameters for on-line leak detection

Grace, I. N.; Datta, Debajit; Tassou, S.A.

doi:10.1016/j.applthermaleng.2004.07.008

Cited by 66 publications

(25 citation statements)

References 2 publications

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“…Examples of FDD studies include chillers [2–5], air handling units [6–9], split air-conditioning systems [10–12], and rooftop units [13–16]. Grace [17] studied the sensitivity of system performance to different refrigerant charge levels. Pak [18] investigated the impact of fouling and cleaning on heat exchanger performance.…”

Section: Introductionmentioning

confidence: 99%

Effect of common faults on the performance of different types of vapor compression systems

Domanski

Payne

2016

Applied Thermal Engineering

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The effect of faults on the cooling capacity, coefficient of performance, and sensible heat ratio, was analyzed and compared for five split and rooftop systems, which use different types of expansion devices, compressors and refrigerants. The study applied multivariable polynomial and normalized performance models, which were developed for the studied systems for both fault-free and faulty conditions based on measurements obtained in a laboratory under controlled conditions. The analysis indicated differences in responses and trends between the studied systems, which underscores the challenge to devise a universal FDD algorithm for all vapor compression systems and the difficulty to develop a methodology for rating the performance of different FDD algorithms.

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Section: Introductionmentioning

confidence: 99%

Effect of common faults on the performance of different types of vapor compression systems

Domanski

Payne

2016

Applied Thermal Engineering

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“…Most of the previous studies are consistent with these results. The previous studies concluded that, with the increase in charge, mass flow rate increases . However, according to two separate research reports published by, the mass flow rate reaches a maximum value at a certain charge and then decreases with further increases in charge.…”

Section: Resultsmentioning

confidence: 94%

“…10 Previous studies show that the increase in refrigerant charge increases the degree of subcooling. 2,6,9,11 Farzad, 12 Rodriguez, 13 and Grace and colleagues 14 investigated the effect of the charge on the refrigerant mass flow rate. They found that the mass flow rate of refrigerant increases with the increase in refrigerant charge, however, two other studies by Martinez-Galvan and colleagues 10 and Chen and colleagues 11 show somewhat different results.…”

Section: Literature Reviewmentioning

confidence: 99%

“…The previous studies concluded that, with the increase in charge, mass flow rate increases. 2,[12][13][14] However, according to two separate research reports published by, 3,11 the mass flow rate reaches a maximum value at a certain charge and then decreases with further increases in charge. The present results suggest such a trend may only be the case at a high room temperature of 35 • C.…”

Section: Effect Of Refrigerant Charge On Mass Flow Ratementioning

confidence: 99%

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Performance of a single‐duct portable propane air conditioning system under different refrigerant charge levels

Siang

Sharifian

2017

Heat Trans. Asian Res.

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The effects of the refrigerant charge on the performance of a portable propane air conditioning system have been evaluated and compared to nonportable systems in which the surrounding temperatures of the evaporator and condenser are not equal. This study aims to determine the similarities and differences in the performance of the two types of propane air conditioners under different charge levels, and to serve as a source of reference for future designs of portable air conditioners. The refrigerant charge was changed from −12.3% to +30% of its normal charge at several room temperatures ranging from 20 °C to 35 °C. The performance parameters include the refrigerant temperature, mass flow rate, maximum velocity of refrigerant, maximum pressure, cooling capacity, compressor work, specific cooling capacity, and coefficient of performance of the system. It has been found that an increase in charge level was found to increase the cooling capacity, coefficient of performance, and maximum velocity of refrigerant in the system while decreasing specific cooling capacity. The increase in the charge caused a relatively insignificant rise in the maximum pressure of the system and useful work of the compressor.

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“…These factors are important for estimating RCA, e.g., the outdoor dry-bulb temperature is essential for determining the fan step of the outdoor unit; therefore, it has considerable influence on the refrigerant flow in the EHP system [57]. Similarly, both subcooling and superheating have been reported to significantly affect RCA [2,13,58]. In addition to factors affecting RCA identified in previous studies [2,13,57,58], this study reveals the effects of three additional factors (i.e., T evap,in , T cond,out , and T comp,out ) on RCA and shows the relationship between RCA and these factors under diverse experimental conditions (Section 3.1).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2020

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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.Sustainability 2020, 12, 2914 2 of 23 and decreased the capacity by~20%; moreover, improper RCA can further reduce the efficiency of on-site ACs by 10-20% [9].In a field study, the refrigerant was improperly charged for~50% of the on-site heating, ventilating, and air-conditioning (HVAC) systems [8,10]. Furthermore, more than half of the residential cooling systems showed improper RCA problems [8]. For the long-term operation of systems, mechanical wear or improper maintenance could lead to refrigerant leakage or overcharge, which, in turn, resulted in reduced system operation efficacy and increased energy consumption [11]. Moreover, improper RCA can result in decreased system performance, increased energy consumption, and reduced life span of the system [12]. In the long run, from an economic point of view, improper RCA can lead to an increase in the operational cost of a building system; thus, if the RCA of a running system in a building can be effectively estimated, it can be positively used to solve the abovementioned problems.The topic of RCA detection is not widely discussed in the literature and only a few studies have been conducted for detecting RCA [13][14][15][16][17]. For example, a polynomial expression-based RCA detection algorithm was developed using only subcooling. The results showed relatively good predictions within a relative deviation of 8.0% [13]; however, although approaches based on mathematical expression models allow accurate predictions of RCA, they are often designed for individual systems, thus making their applications on other on-site EHP systems difficult [2,14]. Moreover, they may require several sensors to implement, thus leading to increase in cost. Other studies r...

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Sensitivity of refrigeration system performance to charge levels and parameters for on-line leak detection

Cited by 66 publications

References 2 publications

Effect of common faults on the performance of different types of vapor compression systems

Effect of common faults on the performance of different types of vapor compression systems

Performance of a single‐duct portable propane air conditioning system under different refrigerant charge levels

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

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