A tailor-made energy concept can automatically reduce power costs and can result in an improvement of your company’s CO2 balance. This was precisely the case for domestic appliance manufacturer Miele & Cie. KG at its Bünde plant.
Through the use of a Combined Cooling, Heat and Power (CCHP) system, with ADsorption chillers by Cleantech company InvenSor GmbH, Miele successfully managed to reduce its energy requirement for cooling. The new energy system has been in effective use since April 2015. It consists of 11 InvenSor ADsorption chillers LTC 10 plus-FC (with Free Cooling function) with a joint cooling capacity of 110 kW and two Viessmann cogeneration units with a total electrical output of 480 kW and a thermal output of 720 kW.
The high overall system efficiency and the long running hours of the cogeneration units are particularly noteworthy, especially during the warmer months. Since then, family-owned Miele has been able to generate its own power for the entire plant.
As a result, the company will in the future be more independent from rising electricity prices imposed by energy providers. The waste heat of the cogeneration plants is used to generate cooling in the ADsorption chillers, which work with water as a natural refrigerant. In winter, the integrated free cooling function of the InvenSor chillers comes into effect, which provides cooling directly via the external air when ambient temperatures are below 15°C. In that case, the waste heat is also available to heat the building in winter.
Innovative and effective
Prior to the implementation of the CCHP system, the company used a boiler system for all ten buildings, which consisted of two separate boiler houses. As a result of restructuring in the Production Division with efficiency measures being implemented, and of additional laboratories in the Development Division, the cooling requirement has recently increased. A solution was required that was both effective and sustainable in the long-term.
With this in mind, Klaus-Dieter Stellbrink, Head of Operational Engineering at the Bünde plant, turned to a local engineering office. Working together, a suitable energy concept was created that perfectly fulfilled the high requirements and that could be implemented without any problem.
The decision was made to use adiabatic recooling units, whereby one is located on the roof of the plant and another alongside the production hall. “As a result of this refurbishment, we managed to supply the entire plant with cooling exclusively from ADsorption chillers.
This means that the traditional chiller used before will be kept operational only for special use,” explains Oliver Tamm, Product Manager at InvenSor. In addition, two buffer tanks were integrated into the system, which serve as heat and cold storages respectively.
The ADsorption cooling capacity should at first be used only for the cooling of the laser systems, the press line for sheet metal and for air conditioning of additional rooms in the Quality Management Department. However, because the cooling systems still had remaining capacity, a decision was quickly made to integrate the server room and the laboratory rooms into the InvenSor cooling system. The chillers were installed off-site at two different locations with a view to positioning the cooling directly alongside the cooling consumer units. In this way both the length of the pipelines and energy losses could be kept to a minimum.
Ideal for in-situ cooling
At the Miele plant in Bünde, 570 employees are responsible for the development and production of hobs, steam cookers and warming drawers. Each year the plant consumes more than 3,900 MWh of electricity and 7,600 MWh of natural gas within a total surface area of 82,600 m2. Because Miele places great value on sustainability, both in its own products and in their manufacture, the decision to opt for environmentally-friendly ADsorption technology was an easy one.
“The cooling systems are perfect for our desired cooling output and ensure smooth operation,” said Thomas Götting, an employee within the Operational Technology Division in Bünde. According to Götting’s projections, the energy cost savings on account of these CCHP systems should amount to approx. 240,000€ each year. An investment that will pay off both financially and ecologically. During the coming years, further projects in the area of cooling are planned at Miele. On account of the great success of the collaboration, the InvenSor ADsorption chillers will again be at the forefront of this. “We received a great deal of support from InvenSor and are thoroughly satisfied with the result,” concluded Mr Götting.
InvenSor ADsorption chillers are among the most user-friendly and reliable devices on the market. The switchover to the sustainable technology begins to pay off with cooling capacities from 10 kW. The systems are used for cooling needs ranging up to 300 kW. Energy cost savings achieved using an adsorption cooling solution are generally up to 70%. The micro-controller developed specifically for the chillers enables a host of configuration options and adjustments to the respective requirements of the overall system and the user.
Technical details of the system
||11 InvenSor LTC ADsorption chillers with a nominal cooling capacity of 110 kW
||2 Viessmann cogeneration units each with outputs of 240 kW el / 360 kW th
||Machine cooling, space cooling