Abstract: A passive water cooler comprising a water tank arranged for containing a volume of water, an internal heat exchanger disposed within the water tank for contact with (e.g. submersion within) said volume of water and an external heat exchanger disposed outside the water tank in thermal communication with the internal heat exchanger. The external heat exchanger and the internal heat exchanger are connected and arranged to collectively define a fluid circulation circuit configured to contain coolant fluid flowable by convection to provide said thermal communication for transferring heat therebetween. The tank comprises thermally insulating material for thermally insulating said volume of water from the environment within which the external heat exchanger resides. The external heat exchanger is arranged to be positioned higher than the internal heat exchanger to permit formation of a thermocline within the coolant fluid between the external heat exchanger and the internal heat exchanger.

Abstract: A passive water cooler comprising a water tank arranged for containing a volume of water, an internal heat exchanger disposed within the water tank for contact with (e.g. submersion within) said volume of water and an external heat exchanger disposed outside the water tank in thermal communication with the internal heat exchanger. The external heat exchanger and the internal heat exchanger are connected and arranged to collectively define a fluid circulation circuit configured to contain coolant fluid flowable by convection to provide said thermal communication for transferring heat therebetween. The tank comprises thermally insulating material for thermally insulating said volume of water from the environment within which the external heat exchanger resides. The external heat exchanger is arranged to be positioned higher than the internal heat exchanger to permit formation of a thermocline within the coolant fluid between the external heat exchanger and the internal heat exchanger.