Optimisation of the throttling system in a CO2 refrigerating machine

Casson, Vanna; Cecchinato, Luca; Corradi, Marco; Fornasieri, Ezio; Girotto, S; Minetto, Silvia; Zamboni, Luca Q.; Zilio, Claudio

doi:10.1016/s0140-7007(03)00077-x

Cited by 32 publications

(13 citation statements)

References 5 publications

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“…[13] and others [14] in air conditioning, Nekså [15,16] in heat pumps where the results are quite good, and some others that are developing new cycle configurations [17,18] and new elements [19,20]. But what is common to all transcritical carbon dioxide applications is the existence of an optimal pressure in the gas-cooler at which the maximum efficiency of the refrigerating cycle is achieved.…”

Section: Introductionmentioning

confidence: 99%

Experimental evaluation of the energy efficiency of a CO2 refrigerating plant working in transcritical conditions

Cabello

Sánchez

Torrella

2008

Applied Thermal Engineering

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Section: Introductionmentioning

confidence: 99%

Experimental evaluation of the energy efficiency of a CO2 refrigerating plant working in transcritical conditions

Cabello

Sánchez

Torrella

2008

Applied Thermal Engineering

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“…They concluded that the capillary tubes allow obtaining the same COP levels as the controllable valves especially at high gas-cooler temperatures. Casson et al [12] analysed theoretically two different throttling systems considering a plant operating in transcritical conditions.…”

Section: Figure 1transcritical Refrigeration Co2 Cycle With Double Ementioning

confidence: 99%

A new approach to optimize the energy efficiency of CO2 transcritical refrigeration plants

Peñarrocha

Llopis

Tárrega

et al. 2014

Applied Thermal Engineering

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This paper proposes a model-free real-time optimization and control strategy for CO2 transcritical refrigeration plants that assures covering the cooling demand and continuous tracking of conditions for maximum efficiency. Our approach obtains the feedback with only three measurements, and controls the opening degree of a back-pressure valve and the speed of the compressor. The strategy minimizes the power consumption of the compressor instead of maximizing the coefficient of performance, which avoids several sensors, and we demonstrate mathematically that both approaches are equivalent. We implemented the strategy with an algorithm that includes two independent auto tuned controllers, one devoted to regulate the high-pressure and another to regulate the outlet temperature of the secondary fluid of the evaporator. It also incorporates a real time perturb and observe procedure to locate on-line the optimum high-pressure that minimizes the compressor power consumption. The paper presents the experimental evaluation of the control strategy, verifying the stable operation of the algorithm and the energy optimization of the plant. KEYWORDS

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“…Then for the best utilisation of such a technology it is necessary that in each working condition the system operates at optimal value of the cycle upper pressure, that is the one which leads to the maximum COP (Lorentzen, 1994;Kim et al, 2004;Casson et al, 2003). Several authors, Inokuty (1923), Kauf (1999), Liao et al (2000), Sarkar et al (2004) and Chen and Gu (2005) faced up the optimisation problem of a transcritical system upper pressure.…”

Section: Introductionmentioning

confidence: 99%