• Solutions to boost the COP of low-medium power transcritical CO2 refrigeration cycles Evaluation an internal heat exchanger (IHX) and a thermoelectric subcooler (TESC) Comparative cooling capacity between IHX TESC Greater improvements obtained in with Discussion strengths weaknesses both technologies for The use carbon dioxide state has become one most used solutions comply F-Gas directive re...

This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO2 and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 C, the energy efficiency of the COOLCEP-S sys...

Compared to mechanical compressors, ejector-based refrigeration systems can make direct use of many forms thermal energy, including waste heat, solar thermal, or biogases. It is known that SE have a lower efficiency compared compressors because their performance at high compression ratios. In the present work, binary fluid ejector heat pumps with are presented based on proper selection fluids a...

A dynamic model of a single-effect absorption refrigeration cycle has been developed. Modeling of the cycle performance requires thermodynamic properties which are obtained from equations of state for refrigerant-absorbent mixtures. The transient response of the absorption refrigeration cycle is investigated using mass, momentum and energy balances for the different parts of the system. Some de...

Abstract The large-scale deployment of ejector refrigeration systems (i.e., solar-based systems), although representing a promising alternative compared with mechanical compressor ones, is hindered due to limitations regarding control modes. Indeed, ejectors are fluid-dynamics controlled devices and, because their fixed geometry, they operate at highest efficiency in narrow range operating cond...

Irreversible effects in thermoelectric materials limit their efficiency and economy for applications in power generation and refrigeration. While electron transport is unavoidably irreversible in bulk materials, here we derive conditions under which reversible diffusive electron transport can be achieved in nanostructured thermoelectric materials. We provide a fundamental thermodynamic explanat...

A cold room assisted vapor-compression refrigeration cycle is dynamically modeled in a year and optimized. Total annual cost (TACO) and coefficient of performance (COP) are selected as two objective functions. Both cold room and refrigeration cycle parameters are considered as design variables. Moreover, three working fluids included R22, R134a and R407c are examined. The optimum Pareto front r...