Transcritical CO2 commercial refrigeration plant with adiabatic gas cooler and subcooling via HVAC: Field tests and modelling

Abstract

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Influence of the Meteorological Record Length on the Generation of Representative Weather Files

“…The findings suggest that also other designing procedures of building systems could be influenced by these differences (considering also the extreme temperatures variations). Among the others, the systems whose efficiency depends on weather conditions should be studied, for example heat pumps [35][36][37], evaporative cooling systems [13,14] or dry coolers [15][16][17] systems, that are relevant for large scale planning, energy savings, water and carbon footprint reduction [38,39].…”

Effect of dedicated mechanical subcooler size and gas cooler pressure control on transcritical CO2 booster systems

“…1 and 2, while the values of the main design parameters and settings are recalled in Table 1. The actual plant allows subcooling at the exit of the gas cooler by exchanging heat with chilled water provided by the HVAC plant [12]. In the present work, a Dedicated Mechanical Subcooler (DMS), that consists of a single-stage cycle working with R1234yf as refrigerant, has been adopted and included in the model, in order to exploit the energy improvements from the use of a dedicated subcooler, free from the penalties of HVAC coupling.…”

“…Subcooling can be achieved not only by employing a dedicated mechanical system, but also through taking advantage of chilled water usually available for air conditioning purposes [12]. A comparison between a DMS scheme, a subcooling scheme with HVAC chilled water integration and the typical configuration with parallel compression, which is commonly considered as an alternative to subcooling, is thus carried out.…”

“…The energy consumption of the BPC is estimated as the sum of the electrical energy consumption of all the compressors, here included the parallel one-. As regards the BSC, the electrical consumption of the subcooling function by the HVAC chiller is estimated by dividing at each time step the cooling power at the subcooler by the COP of the water chiller at the operating conditions at that specific time [12]. It can be noticed that the BDMS scheme, in this example of application and climate, is a bit more effective than the parallel compression scheme BPC and, if optimised, a further small improvement can be achieved.…”

“…The opportunity to uncouple the cooling power generation and the use for subcooling can be exploited by benefitting of cold water storage, as shown by Polzot et al [11] with regard to a fire prevention water reservoir. Cortella et al investigated another plant scheme where the cooling power demand can be satisfied by coupling the refrigeration with the HVAC systems, when this is available [12]. This solution has showed lower performance than other configurations such as the parallel compression of the flash gas, but it can give rise to an economic advantage thanks to the low investment costs.…”