A dynamic model of a vapor compression cycle with shut-down and start-up operations

Li, Bin; Alleyne, Andrew G.

doi:10.1016/j.ijrefrig.2009.09.011

Cited by 141 publications

(84 citation statements)

References 12 publications

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“…These results support the possibility of dividing the system into parts, and this was provided by the literature (ZHAO; ZAHEERUDDIN, 2005;MACKINLEY;ALLEYNE, 2008;LI;. The model proved the first order approximation with time delay between the input variables (F(s) e C(s)) and output variables (Te(s), Tc(s)).…”

Section: Resultssupporting

confidence: 86%

“…Some studies use numerical models based on partial differential equations for the conservation of mass and energy, dividing the system into control volumes (COSTA; LEAL; CARMO JÚNIOR, 2004;LI;MACKINLEY;ALLEYNE, 2008;NOGUEIRA;ZÜRN, 2005;ZHAO;ZAHEERUDDIN, 2005), obtaining important results for the simulation of the transient in cooling systems. Pirozzi and Amendola (2005) applied simulation to explore the rapid cooling of strawberries with forced air, validating the model with experiments, obtaining results that reinforce the importance of numerical models.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Mathematical model for the cold storage of agricultural products

Meneghetti¹,

Tizzei²,

Cappelli³

et al. 2013

Rev. Ciênc. Agron.

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-Studies of control strategies for refrigeration systems observe, among other variables, the dynamic behavior of temperature and the consumption of electrical energy. Aiming to contribute to these studies, this work presents the proposal and validation of a mathematical model for the cooling system of a cold-storage unit. The model approximates the dynamics and interdependence of the variables, to first-order systems with time delay and the summation of effects. The input variables available are the frequency of compressor activation and the thermal load imposed on the unit, and as output variables, the air temperature both at the evaporator inlet and at the centre of the chamber, as well as the electrical power consumed by the compressor. The results obtained were satisfactory, with an error of less than 0.11 °C for the air temperature at the evaporator inlet, of less than 0.09 °C for the temperature at the centre of the chamber, and of less than 1% for the electrical energy consumed.Key words: Variable rotation. Simulation. Agricultural products-storage. Electrical energy-consumption.RESUMO -Os estudos de estratégias de controle para sistemas de refrigeração observam, entre outras variáveis, o comportamento dinâmico da temperatura e da energia elétrica consumida. Com o objetivo de contribuir com estes estudos, o presente trabalho apresenta a proposta e a validação de um modelo matemático do sistema de refrigeração de uma câmara fria. O modelo aproxima a dinâmica e a interdependência das variáveis a sistemas de primeira ordem com tempo de atraso e somatória de efeitos. Como variáveis de entrada tem-se a frequência de acionamento do compressor e a carga térmica imposta à câmara e como variáveis de saída as temperaturas do ar na entrada do evaporador e no centro da câmara, bem como a potência elétrica consumida pelo compressor. Os resultados obtidos foram satisfatórios, com erro menor que 0,11 °C para a temperatura do ar na entrada do evaporador, menor que 0,09 ºC para a temperatura do ar no centro da câmara e menor que 1% para energia elétrica consumida.Palavras-chave: Rotação variável. Simulação. Produtos agrícolas-armazenamento. Energia elétrica-consumo.

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Section: Resultssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

A Mathematical model for the cold storage of agricultural products

Meneghetti¹,

Tizzei²,

Cappelli³

et al. 2013

Rev. Ciênc. Agron.

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“…A model for each component of the cycle has been built based on [21,22], where the expansion valve, the compressor, and the thermal behaviour of secondary fluxes are statically modelled. A dynamical model for each heat exchanger is developed, since their dynamical behaviour is usually at least one order of magnitude slower than the one of the valve and the compressor.…”

Section: Process Modelmentioning

confidence: 99%

“…As stated in [21], and before in [1,13,23,24], the heat exchanger models are developed using the switched moving-boundary method. It splits the heat exchange zone into three variable-length subzones: superheated, two-phase or/and subcooled refrigerant, giving rise to different model representation or also called modes.…”

Section: Process Modelmentioning

confidence: 99%

Multivariable analysis and H ∞ control of a one-stage refrigeration cycle

Bejarano

Alfaya

Ortega

et al. 2015

Applied Thermal Engineering

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“…No information about the transient thermal evolution of the heat exchangers was presented. The dynamic behavior of a vapor compression cycle including the shut-down and start-up was investigated by Li and Alleyne (2010). The authors applied the moving boundary element method with an advanced switching scheme to capture the dynamic transition of the refrigerant state within the heat exchangers.…”

Section: Introduction and Reviewmentioning

confidence: 99%

Transient 1D heat exchanger model for the simulation of domestic cooling cycles working with R600a

Berger

Posch

Heimel

et al. 2015

Science and Technology for the Built Environment

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Generally, domestic refrigerators and freezers are running in non-continuous operation mode most of the time, which is a necessity to match cooling capacity to thermal loads. In currently available domestic appliances this matching is realized either by on/off or variable frequency control of the hermetic compressor, leading to a repetitive and transient change of the system state. In case of longer compressor runtimes when cooling capacity demand is high (e.g. pull down cycles, initial operation) steady state operating conditions might be reached. The cycling transients cause losses in system efficiency, thus they should be reduced or avoided. To understand the complex transient physical processes and to optimize the cooling system efficiency, the use of numerical methods has turned out to be a promising approach. For this reason, a 1D heat exchanger model, which has been successfully implemented in a domestic cooling cycle simulation tool, is presented in this work. The heat exchanger model is a further development of the model being presented in Berger et al. (2012). The same mathematical framework is used for modeling the evaporator and condenser. In order to compute the void fraction, the pressure drop and the heat transfer in case of evaporation and condensation special empirical models, which are proposed in literature, have been implemented. Finally, the numerical predictions are compared to experimental data gained from a purpose-built test rig.

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A dynamic model of a vapor compression cycle with shut-down and start-up operations

Cited by 141 publications

References 12 publications

A Mathematical model for the cold storage of agricultural products

A Mathematical model for the cold storage of agricultural products

Multivariable analysis and H ∞ control of a one-stage refrigeration cycle

Transient 1D heat exchanger model for the simulation of domestic cooling cycles working with R600a

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