The temperature of the cooling medium in machine tools needs to be controlled accurately so as to ensure high-precision machining. The cooling system must also be energy-efficient, versatile, reliable and easy to maintain. Rittal has factored these requirements into the development of a completely new generation of Blue e+ chillers. The result is a liquid cooling system for process plant and machinery that sets a new market standard.
Cooling accounts for up to 15 percent of a machine tool's entire power consumption. The amount of power used is so high because the temperature of the cooling medium needs to be controlled very precisely, with a maximum hysteresis of just 0.5 K. Larger temperature fluctuations would lead to inaccuracies in the workpiece being machined due to thermal expansion of the components
In order to achieve this temperature precision while also meeting the demands for high energy efficiency, Rittal is launching the new Blue e+ series – a chiller generation that enables a huge leap in energy efficiency. The measure of energy efficiency for refrigeration is the Energy Efficiency Ratio (EER), the ratio of cooling capacity to electrical power consumed. Conventional chillers with hot gas bypass control systems have an EER of 1, while an EER of 3 is possible with the new Blue e+ chillers. The basis for this high degree of energy efficiency is a variable speed compressor. Instead of operating the cooling compressor at full capacity and destroying a large part of the cooling power as with hot gas bypass control systems, the inverter-controlled DC refrigeration compressor can provide exactly the cooling output required. This minimises the hysteresis without having to waste cooling power unnecessarily.
Energy savings of up to 70 per cent
To drive the compressors, Rittal uses DC synchronous motors that achieve a higher efficiency than conventional AC asynchronous motors in most areas of operation. An inverter in conjunction with DC radial fans and an electronic expansion valve enables the speed of these motors to be controlled with high precision, which means Blue e+ chillers always operate at the optimum speed. This innovative drive and control technology results in energy savings of up to 70 percent compared to chillers with hot gas bypass control systems. Because the motors are rarely switched on and off, the components also have a longer service life.
A further innovation that Rittal is using in the new chillers is microchannel technology in the heat exchangers. The larger surface in relation to volume for exchanging heat between refrigerant and cooling water enables the quantity of refrigerant to be reduced by up to 55 percent.
Three flexible performance classes
The new chillers are available in three performance classes with cooling outputs of 2.5, 4 and 6 kW (adjustable between 20 and 100 percent). They are highly flexible and can be used at ambient temperatures of -5°C to 50°C. Various pre-configured option packages are available, for example with a more powerful pump, an inverter pump, for outdoor use (down to -20°C), with oil cooling, with integrated free cooler (hybrid operation) or with integral heater to pre-adjust the temperature of the medium.
Intelligent control concept
A control panel with touchscreen displays all messages in plain text. The Blue e+ app already used with Blue e+ cooling units, which communicates with the units using NFC, is also suitable for Blue e+ chillers. This enables wireless transmission of important information and makes life far easier, especially if the configuration includes several chillers. RiDiag III parameterisation and diagnostic software can also be used with Blue e+ chillers. This software can communicate with the chillers via USB and, in the future, will be able to do so via various network protocols using communication modules.
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