A wind tunnel conditions the air flow for testing equipment, such as heat exchangers, over a wide range of conditions. In this paper, a procedure to develop the operating envelope for the tested equipment in a wind tunnel is presented. The temperature and humidity of the air that requires conditioning is controlled and maintained by the combination of cooling coil (or evaporator), heating eleme...

The rehabilitation ol' thc Xinavane sugar factory in Mozambique necessitated a redesign of the evaporator station. The particular arrangement at Xinavane proved to be extremely sensitive to changes i n operating parametcrs. Using this evaporator station as an example, the concept of design robustness (suitability under a range of operating conditions) is introduccd. A rigorous evaporator simula...

In this study, the method of entropy generation minimization (i.e., design aimed at facilitating both heat, mass and fluid flows) is used to improve the evaporator geometry (aspect ratio and fin density) considering the irreversibilities produced by the heat and mass transfer, and viscous flow processes. A fully algebraic semi-empirical model was put forward to simulate the thermal-hydraulic be...

This paper presents the experimental and theoretical assessment of thermal behaviour a roll-bond evaporator in small-scale household refrigerator using refrigerant R600a as working fluid. The data were compared with general correlation employed to evaluate heat transfer convection (HTC) radiation vertical horizontal plates evaporator. is placed at top side refrigerator. To provide right boundar...

A compact, two-stage R-404A / R-508b cascade refrigeration system designed for interface with a high-performance microprocessor is under development. Such a system, designed to remove 100 W at –70 °C, can avoid the high cost of deep cryogenic cooling. Because thermal interface design is critical in maintaining low chip temperatures, a compact, microchannel evaporator is used. A chemically micro...

In most of the Automotive Air Conditioning Systems (AACSs) though the compressor is powered by the car engine, the evaporator blower and the condenser fan are run by a 12-volt DC battery which is powered by an alternator. Any fault in the alternator, drops the battery output voltage. Owing to this, a stationary test rig for an AACS is developed with all actual automotive components. A continuou...

A study is presented on the influence of air flow rate and surface geometry on the thermal-hydraulic performance of commercial tube-fin ‘no-frost’ evaporators. A specially constructed wind-tunnel calorimeter was used in the experiments from which data on the overall thermal conductance, pressure drop, Colburn j-factor and Darcy friction factor, f, were extracted. Eight different evaporator samp...

h = heat transfer coefficient q = heat flux from the wall of evaporator to refrigerant Tw =Temperature at the wall of evaporator Tf = Temperature of the refrigerant kal = Conductivity of aluminum t = Thickness of evaporator M& = Mass flow rate of refrigerant Cp = Constant-pressure specific heat of refrigerant Tsat = Saturation temperature of refrigerant Tin = Temperature of refrigerant at inlet...

Preliminary note This paper presents the exergy destruction of an evaporator or a condenser or evaporator and condenser. The exergy destruction can be analytically calculated by using the same non-dimensional variables which have been used by its energy analysis. The one additional variable is the ratio of absolute input temperatures of both streams. This means that the given model enables the ...

A numerical simulation of a liquid overfeed system working with pure refrigerants in steady state conditions has been performed. The global algorithm is based on the sequential resolution of the different elements of the system (compressor, evaporator, condenser, ... ). For each element, a simplified mathematical model based on global balances of mass, momentum and energy is used. For the evapo...