Heat Recovery - Double Bundle Condenser

Double-bundle condenser or 2-condenser heat recovery can significantly reduce space, domestic water, and/or process water heating costs. Waste heat, normally rejected to the cooling tower, is captured and reused. The example shown here heats water to between 95°F and 120°F to satisfy concurrent cooling and heating loads. The term "double bundle" or split-head condenser refers to one enclosed shell housing two tube bundles separated on the water side.

When the heating load is present, heat is recovered by reducing the amount of heat rejected to the cooling tower. This is done by modulating water flow through (and around) the cooling tower.

As the water temperature returning from the heating load falls, the tower bypass valve diverts and increasing amount of water directly back to the condenser, transferring heat to the heat recovery condenser bundle and maximizing energy recovery. Hot water up to about 130°F can be produced in certain designs. However, the economics of doing this depends on the relative value of power used and heating energy saved. In addition, this evaluation requires a careful consideration of electric and fuel rate structures.

A back-up heat source is required if the chiller waste heat is not sufficient to reliably satisfy the entire heating load. And, the double-bundle condenser heat recovery option must be specified when the chiller is ordered. Obviously, the chiller operates at a higher kW per ton when heating water above ~ 95°F, but this is normally very cost-effective since the COP of heating is high.