Nonisentropic Phenomenological Model of a Reciprocating Compressor

Duarte, Willian Moreira; Pabón, Juan José García; Maia, Antônio Augusto Torres; Machado, Luiz

doi:10.1142/s2010132519500391

“…For the discharge temperature, the uncertainty of the model was 50% higher than that obtained experimentally. The higher uncertainty of the discharge temperature calculated by the model than the discharge temperature was also found in the study present by Duarte et al [104].…”

Section: Dx-sahp Model Validationsupporting

confidence: 82%

Experimental Validation Through a Parallel Computation Algorithm for Evaluation Uncertainty of the Mathematical Model of Direct Expansion Solar Assisted Heat Pump

Duarte

¹

,

Paulino

²

,

Duarte

³

et al. 2023

J. Solar Eneg. Res. Updat.

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This paper presents the development of a mathematical model for a direct-expansion solar-assisted heat pump (DX-SAHP) operating in steady-state. The mathematical model was implemented using the scientific software EES and using a code written in Python. It was utilized a lumped parameter model for the heat exchangers and a semi-empirical model for the compressor. The mathematical model was validated using experimental data of a DX-SAHP running with R134a. Two hundred simulations were made combining different correlations for estimating the convective heat transfer coefficient in the evaporator/collector. The Mean Absolute Deviation (MAD) and the Mean Deviation (MD) between the theoretical and experimental values for the COP were 2.6±1.8 % and 0.9±1.8 %, respectively. The MAD and MD between the discharge temperature were 1.56±0.16 % and -1.45±0.16 %. The mean difference between the results using EES and Python were 1.4 %. The use of Python with parallel computing for uncertainty analyses, reduced the simulation time in 88 % if compared with EES. The model in Python is available as open-source through the platform Google Colaboratory.

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“…In addition, mechanical losses are transferred to the fictitious wall, and they are calculated with the use of an energy balance expressed by Equation (12).…”

Section: Heat Transfermentioning

confidence: 99%

“…As the main component of a heat pump or refrigeration system is the compressor, whose performance greatly affects the overall system performance 8 , many methods have focused on modeling this component with high detail, relying on various numerical techniques. Aiming to develop a multi-purpose numerical model suitable for a wide range of positive displacement machines including both compressors and expanders Bell et al 9 and Ziviani et al On the other hand, focusing only on reciprocating compressors, Duarte et al 12 and Navarro et al 13 presented numerical models for steady state modeling while Yang et al 14 developed a comprehensive model taking into consideration compression process, geometry and kinematics, valves and leakages, heat transfer and frictional power losses sub-models. Ndiaye and Bernier 15 extended their model for unsteady/ dynamic conditions for simulating the on-off operation on hermetic reciprocating compressors.…”

Section: Introductionmentioning

confidence: 99%

Methods based on a semi-empirical model for simulating scroll compressors with HFC and HFO refrigerants

Meramveliotakis¹,

Kosmadakis²,

Karellas³

2022

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The aim of this work is to evaluate three methodologies regarding semi-empirical scroll compressor modeling for different refrigerants and conduct a comparative analysis of their results and accuracy. The first step is to improve a semi-empirical model for scroll compressors based on established techniques, and further enhance the physical background of some of its sub-processes leading to more accurate predictions. Focus is then given on the compressor operation when changing the refrigerant, proposing three methods in total. The first method refers to the standard model, requiring an optimization process for the calibration of all the model parameters. The second method relies on a reference refrigerant, and also uses optimization procedures, but for the fine-tuning of a small subset of the parameters. The third method is more generalized, without the need of any optimization process for the parameters identification, when fluid change occurs, leading to a very fast approach. Το evaluate the accuracy and verify the applicability of each method also related to the necessary computational time, two scroll compressors each with three different refrigerants are considered (HFCs and HFOs and their blends). The model is evaluated with the available manufacturer data, using R134a as reference refrigerant. The results show that the first method predicts the key indicators with a very high accuracy, with the maximum discrepancy of 2.06%, 4.17% and 3.18 K for the mass flow rate, electric power and discharge temperature respectively. The accuracy of the other two methods is dropping, but within acceptable levels in most of the cases. Therefore, in cases that reduced accuracy can be accepted, the third method is preferred for compressor performance prediction when changing the refrigerant, which provides results at a small fraction of time compared with the other two methods, once the parameters are calibrated for a reference case.

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“…On the other hand, focusing only on reciprocating compressors, Duarte et al 14 and Navarro et al 15 presented numerical models for steady state modeling while Yang et al 16 developed a comprehensive model taking into consideration compression process, geometry and kinematics, valves and leakages, heat transfer and frictional power losses sub-models. Ndiaye and Bernier 17 extended their model for unsteady/ dynamic conditions for simulating the on-off operation on hermetic reciprocating compressors.…”

Section: Introductionmentioning

confidence: 99%

Methods based on a semi-empirical model for simulating scroll compressors with HFC and HFO refrigerants

Meramveliotakis¹,

Kosmadakis²,

Karellas³

2022

View full text Add to dashboard Cite

The aim of this work is to evaluate three methodologies regarding semi-empirical scroll compressor modeling for different refrigerants and conduct a comparative analysis of their results and accuracy. The first step is to improve a semi-empirical model for scroll compressors based on established techniques, and further enhance the physical background of some of its sub-processes leading to more accurate predictions. Focus is then given on the compressor operation when changing the refrigerant, proposing three methods in total. The first method refers to the standard model, requiring an optimization process for the calibration of all the model parameters. The second method relies on a reference refrigerant, and also uses optimization procedures, but for the fine-tuning of a small subset of the parameters. The third method is more generalized, without the need of any optimization process for the parameters identification, when fluid change occurs, leading to a very fast approach. Το evaluate the accuracy and verify the applicability of each method also related to the necessary computational time, two scroll compressors each with three different refrigerants are considered (HFCs and HFOs and their blends). The model is evaluated with the available manufacturer data, using R134a as reference refrigerant. The results show that the first method predicts the key indicators with a very high accuracy, with the maximum discrepancy of 2.06%, 4.17% and 3.18 K for the mass flow rate, electric power and discharge temperature respectively. The accuracy of the other two methods is dropping, but within acceptable levels in most of the cases. Therefore, in cases that reduced accuracy can be accepted, the third method is preferred for compressor performance prediction when changing the refrigerant, which provides results at a small fraction of time compared with the other two methods, once the parameters are calibrated for a reference case.

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Nonisentropic Phenomenological Model of a Reciprocating Compressor

Cited by 9 publications

References 14 publications

Experimental Validation Through a Parallel Computation Algorithm for Evaluation Uncertainty of the Mathematical Model of Direct Expansion Solar Assisted Heat Pump

Experimental Validation Through a Parallel Computation Algorithm for Evaluation Uncertainty of the Mathematical Model of Direct Expansion Solar Assisted Heat Pump

Methods based on a semi-empirical model for simulating scroll compressors with HFC and HFO refrigerants

Methods based on a semi-empirical model for simulating scroll compressors with HFC and HFO refrigerants

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