V. BLOMENHOFER (1), T. Becher (1), W. Russ (2), K. Wasmuht (1); (1) Ziemann International GmbH, Ludwigsburg, Germany; (2) Hochschule Weihenstephan-Triesdorf, University of Applied Sciences, Freising, Germany
Over 40% of the total electricity consumption in breweries is utilized for refrigeration processes with electrically driven compressors (state-of-the-art). Cooling capacity is required in several production steps, such as bright beer tanks, beer and hop storage, beer fermentation, ice water for wort cooling, etc. The aim of the current work is to replace parts of the conventional cooling capacity in breweries by natural and renewable cooling energy in the form of snow. The novel idea is to produce high-density snow with modern technology combined with the atmospheric wet-bulb temperature for technical implementation in breweries. The developed system has a 50–70 higher COP (coefficient of performance ~ 210) than a classical refrigeration plant (COP ~ 3–4). The produced snow and its enthalpy is utilized to cool water by means of the melting process for further cooling applications. The system consists of several snow lances with a compressed air source, a basin with a horizontal separating wall for the two aggregate states of water (solid, fluid), a heat exchanger, and pumps. According to the defined atmospheric wet-bulb temperature <–1.5°C, snow is produced whenever possible. The high-density snow cools the water below the separating wall by means of the melting effect (melting enthalpy). The water is cooled and led, for example, to a glycol heat exchanger. From there the cooling energy is distributed within the brewery. The key factor of this novel approach to producing cooling energy is the wet-bulb temperature, which depends on the air humidity and dry-bulb temperature. For example, a dry-bulb temperature of +8.3°C combined with an air humidity of 50% leads to a wet-bulb temperature in the atmosphere of –1.5°C. Today, ice-forming technologies such as snow lances have a great ability to produce large amounts of snow (45 m3/hr, excluding compressed air and water pressure), depending on the wet-bulb temperature. A medium-sized brewery, which has a theoretical demand for cooling energy of approximately 1.1 million kWhr (kilowatt-hour per year, 127 kW) serves as example. In 2012 approximately 10% of the annual hourly temperature values (8,784 hr/year) achieved a wet-bulb temperature of <–1.5°C in the months of December, January, and February. With a specific value of 3.8 m3 of snow production per kilowatt-hour (including compressed air and water pressure), the entire cooling energy of the brewery could theoretically be covered by snow throughout the year. In practice, the size of the basin would be enormous due to the large amount of snow. Based on realistic snow coverage per month, it is possible to produce the quantity of snow required for one month in an operating time of 38 hr. In fact, the quantity of snow for three months of production and one month of storage can be easily implemented.
In 2009 Verena Blomenhofer completed her studies as a graduate engineer in chemical and bioengineering at the University of Erlangen-Nuremberg. Afterward, she participated in a cooperative project between the Chair of Fluid Mechanics/University of Erlangen-Nuremberg and Ziemann International GmbH and worked as a Ph.D. student in the field of research and development for 3.5 years. Her Ph.D. thesis will be completed by the middle of 2014. Since the beginning of 2013 she has been working in the R&D/Process Technology Department at Ziemann International GmbH, with a focus on environmental/energy topics and in the field of intellectual property rights.