Direct contact heat exchanger with ice generation (DCHI)

Cold water at approx. 0-1 °C (ice water) is used on a large scale for cooling purposes, especially in dairies.

Refrigeration plants for making ice water and heat pumps based on cold sources such as sea, ground or waste water is challenged by the risk of ice formation when the evaporating temperature approaches freezing. In a conventional refrigeration and heat pump system freezing will lead to shutdown of the plant, or, provided the evaporator is designed for it, a drop in suction pressure (evaporation temperature) with significant deterioration in both performance (COP) and capacity.

This project will develop a compact, efficient and inexpensive direct contact heat exchanger for water vapor based refrigeration plants allowing ice generation.

A unique, competitive and energy efficient water vapor compressor is under commercialization for chiller application. With the developed heat exchanger, this compressor could be used for very efficient ice water production and heat pump operation in sea, fresh water and low-temperature cooling water. Water vapor is sucked directly from the water surface and ice will be formed as small ice crystals directly without adversely affecting COP and performance as the suction pressure does not drop. Ice formation is thereby reversed to something positive.

In addition to the energy efficient production of ice-water and ice at 0 °C, direct contact heat exchangers could be used for cooling/heat recovery from wastewater (where fouling of the surfaces in traditional heat exchangers is a major problem), for energy efficient ice production, freeze concentration and low temperature concentration.