C O N T E N T S

D’UNE DÉTENDEUR À EJECTEUR UTILISANT LES FLUIDES
R134 ET HFO1234 yf
par
LATRA BOUMARAF, PHILIPPE HABERSCHILL et AHMED
BENSAFI
Abstract. A vapor compression refrigeration system using an
ejector instead of a throttling valve to recover some of the kinetic energy
of the expansion process is presented. A constant-area mixing model for
the two phase flow ejector was developed. For typical air conditioning
operation conditions, the effects of the ejector geometrical parameters
and the pressure drop in the receiving section on the system performance
were investigated. For a set ejector geometry, the condensation
temperature influence on the ejector performance was also studied. The
ejector model is then used to perform the thermodynamic analysis of the
refrigeration system operating with the working fluids R134a and its
potential substitute HFO1234 yf. The simulation results show an
important improvement of the relative COP of the ejector expansion
refrigeration system particularly when the condensation temperature
increases (40% at 55°C for the two refrigerants). The results also show
that HFO1234 yf leads to better performance than R134a when the
condensation temperature decreases.
Keywords: refrigeration system, ejector, R134a, HFO1234yf .
REFROIDISSEMENT D’UN COMPOSANT ÉLECTRONIQUE
PAR CONVECTION FORCÉE À L’AIDE DE DEFLECTEURS
LONGITUDINAUX
par
AHLEM ARFAOUI OMRANI, REJEB BEN MAAD, MOURAD
REBAY, COLETTE PADET and JACQUES PADET
Abstract. The cooling of electronic components raises a great deal
of research work, some of which was devoted to the influence of baffles
meant to flow channeling [1]. Therefore, we propose an experimental and
numerical study of the convective transfer of a heating element mounted
on a flat plate placed at the entrance of a laminar flow of air with uniform
velocity. Two longitudinal baffles mounted on the base of the heating
element guide the flow onto it. The results obtained show the influence