Development and performance mapping of a multi-ejector expansion work recovery pack for R744 vapour compression units

Abstract

Development and performance mapping of a multi-ejector expansion work recovery pack for R744 vapour compression units, AbstractA multi-ejector expansion pack, intended as a substitute for a standard high-pressure electronic expansion valve (HPV), was designed, manufactured and experimentally investigated. Four different ejector cartridges were sized to enable a discrete opening characteristic with a binary profile for a parallel-compression R744 system. The system is rated for 70 kW at a 35 °C gas cooler outlet temperature and a -3 °C evaporation temperature. High values of ejector efficiency, exceeding 0.3 over a broad operation range, were recorded for all four of the cartridges tested under vapour compression conditions. The applicability of the multi-ejector pack as a main flashing device was verified experimentally. Similar profiles of the discharge pressure control error were recorded for both alternative options: expansion purely in the HPV vs. HPV-assisted expansion in the multiejector pack.

Performance comparison of fixed- and controllable-geometry ejectors in a CO2 refrigeration system

“…These parameters were set to represent the most typical operating conditions of supermarket refrigeration units operating under warm climate conditions (Banasiak et al, 2015;Hafner et al, 2014). The values in this table are sorted in ascending order of the absolute pressure at the motive nozzle.…”

Application range of the HEM approach for CO2 expansion inside two-phase ejectors for supermarket refrigeration systems

“…1. The more detailed information about the refrigeration unit are presented in the paper of Banasiak et al (2015).…”

“…The range of considered inlet parameters was typical for ejectors operating in refrigeration installations of supermarkets (Hafner et al (2014), Banasiak et al (2015)). …”

“…The geometrical parameters of the ejector motive nozzles of the multi-ejector unit(Banasiak et al (2015)) …”

STUDY & REVIEW ON THE PERFORMANCE ANALYSIS OF VARIOUS EXPANSION DEVICES IN VAPOUR COMPRESSION REFRIGERATION SYSTEM

“…al. [9] studied the multi ejector expansion system for R744 vapour compression units on system rated for 70kW at 35 degree Celsius outlet temperature of gas cooler and -3 degree Celsius of evaporator temperature for four cartridge sized for ejectors system and this system was analyzed & verified experimentally. Multi ejector block system retains the dynamic operational characteristics and precise control of discharge pressure with load variations and atmospheric conditions.…”