Direct product cooling

Ice water systems as washing line for fruit and vegetables

Ice water is required for the washing lines in all fruit and vegetable processing plants. This ice water is then usually to be produced with a state-of-the-art refrigeration system and the washing lines are to be supplied with a constant temperature of +1°C. In the same plants hot water is usually also required for cleaning purposes. The clarification of the power requirement of the refrigeration plant considers the ice water and hot water requirements. In most cases, it is found locally that this fluctuates greatly depending on the season.

In view of the specific needs of heat transfer in the case of direct product cool down, we provide the calculations and the manufactured technical systems as well as components. Consequently, both are tailored to functionality and efficiency, but also never loose sight of process stability of the respective field of application.

Our ice water systems, falling film chillers, ice banks or heat exchange systems have this stability to ensure that the direct product cooling process chain is not interrupted.

There are not many cooling systems that allow water to be cooled down to +0.5°C. Usually, there are only two alternatives, the falling film chiller and the static ice bank It quickly becomes clear that an ice storage system can be operated more energetically by taking advantage of the favourable low tariff period. However, this argument is directly offset by the much lower investment costs of the falling film chiller. After examining the running time of the refrigeration system, there are usually indications that the optimal balance between investment costs and operational reliability for charging a certain kW value for an ice storage system is achieved, but the argument that actually decides everything is outweighed by the necessary hourly withdrawal of ice water in the processing process and overlaps of the withdrawal with low-tariff times.
 

Energy consumption advantage of a BUCO Industrial Ice machine in direct product cooling

To produce ice, we do have the efficiency in prior focus. Only by melting of the ice, the heat for cooling of the water is taken from the surrounding. Ice is melting at a temperature of 0°C to water and gives 335 kj per kg ice. Therefor we do produce ice with an evaporation temperature T0= -10°C, which generates ice at a temperatures of  T= -0.5°C to -1.0°C. The idea is simple, as the cooling gain for subcooling of the Flake Ice in conventional drum systems is down to T= –8°C, which is only approx. 8% of a higher melting capacity. Unfortunately this has a high energy consumption impact for the drum ice machines as such:

Alternative primary refrigerants and secondary refrigerants

In the selection of refrigerants, today's choice falls on the one hand on natural refrigerants such as NH3, CO2 or propane, and on the other hand on refrigerants such as R448A, R449A, R407A, R407C or R507C. In addition, systems are increasingly being operated with refrigerants such as propylene and ethylene glycol-water mixtures in various concentrations. When choosing the refrigeration concept, a flooded system is usually selected for refrigerants for reasons of low operating costs. For refrigerants with temperature glide, all units are designed for dry expansion (dx operation). Here, flooded evaporators are not used. Finally, in order to make the right decision, many individual aspects have to be considered, evaluated and calculated. In the end, this determines the choice of a falling film chiller or a static ice bank, depending on the advantage calculated on the basis of current data.