In the present work, the performances of improved two-stage multi inter-cooler trans- critical carbon dioxide (CO2) refrigeration cycles with ejector and internal heat exchanger have been examined. In the new improved cycles, an internal heat exchanger is append to the cycles. Also, second inter-cooler in improved cycles, cooled with the refrigeration of the cycle, so that in first c...

The heating capacity and coefficient of performance (COP) of conventional air-source heat pumps decreases towards lower ambient temperatures. In addition, high discharge temperature at the compressor discharge might limit the operation of the heat pump at very low ambient temperatures. Oil injected into the compression chamber at the beginning of the compression process can absorb part of the h...

The utilization of condensate water as a compressor-discharge cooler results in subcooling on the condenser outlet. On other hand, split-type air conditioner (A/C) with R32 working fluid can provide higher temperatures than refrigerants used same A/C. Therefore, A/C R32, equipped heat exchanger by utilizing waste-condensate cooler, has promising potential to produce largest effect air-condition...

In this paper, exergy and exergoeconomic analysis is performed on the recently proposed process forthe coproduction of liquefied natural gas (LNG) and natural gas liquids (NGL) based on the mixedfluid cascade (MFC) refrigeration systems, as one of the most important and popular natural gasliquefaction processes. To carry out this analysis, at first, the proposed process is sim...

if an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. this mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. howeve...

If an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. Air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. This mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. Howeve...

This article presents the results of the experimental runs of a prototype of R744 (CO2) refrigeration system operating in a both air conditioning and heat pump mode when heat rejection is done in supercritical region. The prototype system is sized for a compact car. Data presented are in the limited range of operation. Further optimization and extension of operating range is underway. Test faci...

Air pre-cooling equipment is normally being employed in air-conditioning systems for pre-cooling the ambient outdoor air to enhance the air-conditioning systems performance. In this study, the potential of a passive water-to-air heat pipe based heat exchanger (HPHEX) for air pre-cooling purpose in air-conditioning systems for the high cooling load demanding regions of Iran was investigated. To ...

In this study, an integrated structure of the air separation unit, natural gas liquids recovery equipped with nitrogen removal unit is developed. In this regard, advanced exergy and exergoeconomic analyses are used to examine the irreversibility, possible improvements and the cost of the inefficiencies of the process. The exergy analysis presents information on the origin of the irreversibility...

Fin-and-tube heat exchangers have been extensively used in many fields, especially heat, ventilation, air-conditioning, and refrigeration systems. In the case of operation a fin-and-tube exchanger as an air cooler, frost formation is important effect that should be taken into account. The accumulation process undesirable since it deteriorates transfer due to insulation layer well causing excess...