The effect of condenser temperature on the performance of the evaporator in a wickless heat pipe performance

•Study the effect of condenser temperature on the performance of a wickless heat pipe.•Performance in microgravity declined as the condenser temperature decreased.•Temperature data was used to extract a heat transfer coefficient in the evaporator.•Nusselt number was found to scale with Marangoni number to the -1/3 power.•A single correlation using the Marangoni number collapsed all the experimental data.