The effect of temperature on the gas hold-up and flow regimes for air-water and air-electrolyte solutions (NaCI and CuCI,) was studied in a bubble column with a sintered glass disc distributor. For the air-water system, the gas hold-up was found to decrease with increase in temperature. For the air-electrolyte solutions, increase in temperature resulted in increased gas hold-up at lower gas velocity, while at higher gas velocity the gas hold-up was found to decrease with temperature. The gas velocity uy7. for transition from bubble flow to churn turbulent flow was found to decrease with increase in temperature as a result of increased coalescence. In the presence of electrolytes, uR7. was found to be higher than that for water.On a CtudiC I'influence de la tempkrature sur la rktention des gaz et sur les dgimes d'Ccoulement pour des solutions air-eau et air-Clectrolyte (NaCI et CuC12) dans une colonne a bulles munie d'un disque en verre frittk comme distributeur. La rktention des gaz diminue dans le cas du systkme air-eau lorsque la temperature augmente. Pour les solutions air-Clectrolyte, une augmentation de la tempirature provoque une augmentation de la rktention des gaz basse vitesse tandis qu'a plus haute vitesse de circulation des gaz, la retention diminue avec la tempkrature. On a trouve Cgalement que la vitesse des gaz uIT correspondant a la transition d'un Ccoulement malax&, diminue lorsque la tempkrature augmente en raison d'une coalescence accrue. uyl. s'avkre plus ClevC en presence d'Clectrolyte qu'en prCsence d'eau.knowledge of flow regimes and gas hold-up is most A essential in the design of bubble column reactors,

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An experimental study has been carried out on a continuously operated pilot fractional distillation column equipped with an external heat pump. The distillation column was a 153 mm diameter stainless steel unit containing fourty‐four sieve plates. An ethanol‐water mixture was fed to the column and the heat pump working fluid was R114. The actual coefficient of performance (COP)A of the heat pump increased with an increase in the mass flow rate of the working fluid. A maximum value of 4.5 was obtained with a gross temperature lift of 45°C. The performance of two reciprocating compressors was compared. A heat pump effectiveness factor of 0.8 was achieved. A maximum relative contribution of the heat pump of 65 per cent was obtained with minimum temporary insulation. With good insulation it is estimated that the relative contribution of the heat pump should exceed 80 per cent at the design feed rate. No control problems were encountered in the experiments.