The introduction of new refrigerants into the marketplace to replace CFC's banned by the Montreal Protocol has generated new research, required a review of many refrigeration concepts, and has raised new safety issues. One aspect that required further study occurred because some of the new refrigerants have a higher working pressure in the refrigeration and air conditioning equipment. This caus...

The use of carbon dioxide (CO2) as a refrigerant is recently considered for an increasing number of various applications including low capacity transcritical processes. Due to the fluid properties of CO2, the pressure ratio of the refrigeration process is rather low compared to common refrigeration processes while the pressure difference is high. Furthermore, the volumetric capacity of CO2 is h...

Display cases in supermarket systems often exhibit synchronization, in which the expansion valves in the display cases turn on and off at exactly the same time. The study of the influence of switching noise on synchronization in supermarket refrigeration systems is the subject matter of this work. For this purpose, we model it as a hybrid system, for which synchronization corresponds to a perio...

the potential of extracts prepared from seeds of three citrus species (orange, lemon and grapefruit) to stabilize lipid oxidation of cooked and raw broiler meat under refrigeration storage was evaluated and compared with butylated hydroxyl anisole (bha), a synthetic antioxidant. the citrus seed extracts were separately applied at a rate of 1.5% of the weight of the meat. there was a negative co...

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) recently completed the second phase of its Low Global Warming Potential Alternative Refrigerants Evaluation Program (Low-GWP AREP). This industry-wide cooperative research program identified and evaluated promising alternative refrigerants over the past five years. Seventeen low-GWP refrigerants were tested during the second phas...

Fifty milk samples were assessed for prevalence and enumeration of coliform bacteria under refrigeration. Refrigeration exerted profound effect conferring diminished growth of Citrobacter, Enterobacter and Serratia, however, itfavoured Salmonella, E.coli and Klebsiella on other hand. Among them, Salmonella appeared with highest load both in pre-refrigerated (23%) as well as post-refrigerated (4...

Three cases of death are described where all the refrigerated skull of corpses showed cranial base fracture. A question arose whether these fractures were caused by head injury. As the details were clear and both autopsy and relative pathological findings displayed nothing positive, it was presumed that the cranial base fracture was due to the expansion of brain volume and increased intracrania...

Stephan Bachmann, Danfoss Refrigeration & Air Conditioning, Offenbach Lately we have received a lot of customer questions about using electronic expansion valves, so the eighth instalment of Fitters Notes is entirely dedicated to this topic. Optimal evaporator filling (even with large load variations), flexible MOP points, and using the highest possible evaporating temperature in order to incre...

We demonstrate quantum-limited electronic refrigeration of a metallic island in a low-temperature microcircuit. We show that matching the impedance of the circuit enables refrigeration at a distance, of about 50 microm in our case, through superconducting leads with a cooling power determined by the quantum of thermal conductance. In a reference sample with a mismatched circuit this effect is a...