Defrosting in supermarket refrigeration systems is normally controlled by a preset time cycle with most display cabinets timed to defrost every 6 hours. It is widely acknowledged that timed defrost may cause a number of unnecessary defrost cycles and this reduces the energy efficiency of refrigeration systems as well as the accuracy of temperature control of the cases. This paper investigates t...

In this paper, an LNG BOG re-liquefaction system operating according to the Claude refrigeration cycle using oxygen as refrigerant is analysed. It includes a comprehensive exergy analysis of a BOG reliquefaction system installed onboard an LNG carrier. Commonly operating data have been used to carry out a thermodynamic analysis of the system. The system is basically made of two parts: Oxygen cy...

Transient simulations of refrigeration cycles are crucial for evaluating new refrigerants. Previously developed transient simulation tool was capable of simulating refrigeration systems using refrigerants R22 and R134a and was validated with experimental data; however, incorporating non-traditional refrigerants such as R744 (carbon dioxide) change the cycle operation beyond the capabilities of ...

A new model is presented to describe an irreversible absorption refrigerator, in which not only the irreversibilities of heat conduction but also the irreversibilities resulting from the friction, eddy and other irreversible effects inside the working fluid are considered. The influence of these irreversible effects on the performance of an absorption refrigerator with continuos flow is investi...

This paper attends to demonstrate the usefulness of Design of Experiments (DOE) method in magnetic refrigeration (MR) understanding and optimization. A numerical DOE is applied to a simple 1D finite difference model describing an Active Magnetic Regenerative Refrigeration (AMRR) system. The heat transfer fluid is water, the regenerator consists of stacked gadolinium plates and the model is base...

Studied is a kind of NH3/CO2 two-stage low temperature refrigeration system, in which NH3 is used as the refrigerant in the high-temperature stage and CO2 is used as the refrigerant in the low-temperature stage. The performance of the system is simulated and analyzed by changing the mean temperature of the evaporator-condenser and the temperature of the condenser. The mean temperatures of the e...

The vortex tube is a structurally simple device with no moving parts that is capable of separating a highpressure flow into two lower pressure flows with different energies, usually manifested as a difference in temperatures. The vortex tube is relatively inefficient as a stand-alone cooling device but it may become an important component of a refrigeration system when employed as an alternativ...

Iran’s vast common natural gas resources and the necessity to extract and export it as Liquefied Natural Gas (LNG) to distances more than 3000Km opens a lucrative field for researchers to optimize LNG cycles. In this article heat integration in cryogenic cycles by determining interacycle partition temperature and optimizing refrigeration features like Subcooler, Presaturator, aftercooler, reboi...