Monday August 26, 2019 from 10:30 to 12:10
Modelling and development of high-pressure-lift ejector for low temperature evaporators in R744 refrigeration systems for supermarkets
Krzysztof Banasiak1, Ángel Á. PARDIÑAS2, Ekaterini E. Kriezi3, Armin Hafner4.
1SINTEF Energy Research, Trondheim, Norway; 2Department of Energy and Process Engineering, NTNU, Trondheim, Norway; 3Danfoss, Nordborg, Denmark; 4Department of Energy and Process Engineering, NTNU, Trondheim, Norway
Decreasing the complexity of R744 commercial refrigeration systems could substantially reduce their cost, promoting worldwide spreading.
Typically, the share of the low temperature (LT) load in the total load for R744 systems for supermarkets is low. Nevertheless, significant investments must be made to cover this demand, including dedicated compressors, inverter, desuperheater, etc.
The objective of this paper is to describe and numerically validate a new concept based on high-pressure-lift ejector to support LT evaporators. This solution reduces the cost of the system by replacing a whole LT compressor section with a fixed geometry ejector. In addition, elimination of the compressor(s) allows overfeeding operation of LT evaporators.
The paper explores application range of this concept, using a 0-dimensional model of the refrigeration system. In addition, ejector geometry was designed for a typical supermarket capacity and tested numerically in both rated and off-design conditions with use of the in-house developed 1-dimensional code.