Abstract: An exemplary heat exchange system includes a first stage including a first stage heat exchanger and a tower wherein the first stage heat exchanger exchanges heat between a fluid and air to thereby heat the air and generate air convection in the tower; and a second stage including a second stage heat exchanger and a powerable convection unit wherein the second stage heat exchanger receives the fluid from the first stage and exchanges heat between the fluid and air. An exemplary method includes transferring heat energy from a fluid to air using a first heat exchanger to cause air convection in a tower; and transferring heat energy from the fluid to air using a second heat exchanger and a fan. Various other exemplary systems and methods are also disclosed.

Abstract: An unglazed transpired solar collector using solar radiation to heat incoming air for distribution, comprising an unglazed absorber formed of low thermal-conductance material having a front surface for receiving the solar radiation and openings in the unglazed absorber for passage of the incoming air such that the incoming air is heated as it passes towards the front surface of the absorber and the heated air passes through the openings in the absorber for distribution.

Abstract: A system for programming and controlling the rate at which an agricultural chemcial (e.g., fertilizer) is supplied to the water in an agricultural irrigation system. In one embodiment the system is combined with a center pivot irrigation system having a vertical water feed pipe, a horizontal boom, and a chemical supply connected to the feed pipe. A rotation sensor determines the degree of rotation of the boom and a controller controls the amount of chemical supplied to the feed pipe. The system enables the amount of chemical applied to be varied from one section of a field to another.

Abstract: A system for programming and controlling the rate at which an agricultural chemical (e.g. fertilizer) is supplied to the water in an agricultural irrigation system. In one embodiment the system is combined with a center pivot irrigation system having a vertical water feed pipe, a horizontal boom, and a chemical supply connected to the feed pipe. A rotation sensor determines the degree of rotation of the boom and a controller controls the amount of chemical supplied to the feed pipe. The system enables the amount of chemical applied to be varied from one section of a field to another.