Free convection cooling method and apparatus

Claim 1

In a system positively circulating a transport fluid for heat absorption purposes, a method of removing excess heat from such fluid by natural convection circulation of a heat sink liquid not consumed in the heat transfer process, including the steps of locating a heat exchanger in a tank containing a relatively cool heat sink liquid, completely submerging the heat exchanger in the contained liquid beneath the surface of the liquid in said tank and orienting it so that liquid is free to occupy and pass through vertical open flow passages therein, and of flowing the transport fluid through relatively narrow passes in said heat exchanger under forced circulation in heat transfer relation to liquid in said passages, convection currents of flowing liquid being thereby created in said tank flowing upward through said vertical flow passages, the transport fluid being put through said heat exchanger in a circuitous path taking it sequentially in heat transfer relation to upper and lower parts of said vertical flow passages, said heat exchanger providing vertically superposed horizontal flow passages for the transport fluid in alternating adjacent relation to said vertical flow passages and defining said relatively narrow passes, said horizontal flow passages being of substantially greater length than said vertical flow passages, upper and lower horizontal flow passages communicating with one another at one side of the heat exchanger and being separated at the opposite side of the heat exchanger for in flow and out flow of the transport fluid, in-flowing transport fluid first entering upper horizontal flow passages for crossflow through the heat exchanger to said one side thereof then counterflowing to lower horizontal flow passages and then cross flowing in the opposite direction to exit from the heat exchanger at the said other side thereof.