Jens Hesselbach

CO2 and thermal gradient based demand-driven stratified ventilation—Experimental and simulation study

Industrial production processes often emit air pollutants that have adverse health effects and affect product quality. Essentially, several mechanisms, such as mixed and stratified ventilation systems, have been established in companies to remove generated thermal and mass loads from manufacturing areas. The widely used mixed ventilation generates a homogenous temperature and pollutant level in the entire production hall. However, fresh air supply is only needed in the area that is used by employees and needed for processes. As most factories do not adjust the ventilation system to current production conditions, the production hall is over-supplied with clean and conditioned air during idle times. This study describes experimental measurements and simulation analysis to compare mixed and stratified ventilation systems. The measurements include carbon dioxide and temperature profiles with various intake airflows, intake air temperature, thermal load, and machine layouts. Results show advantages in airflow, air quality, cooling capacity, and energy demand when using automatically demand-driven stratified ventilation. The experimental results validate the thermal simulation results. Controlling the layer height, ambient temperature of the room, and concentration of contaminants are vital parameters.

Reducing energy demand in production environment requiring refrigeration—A localized climatization approach

Food and pharmaceutical refrigeration areas place significant demands on air temperature and air humidity control. This leads to high energy requirements on the HVAC system. In the majority of cases, the entire production hall is “over conditioned” with fresh air. However, very often the products are located in a small part of the overall production area (hall). From an energy efficiency and sustainability point of view, it makes sense to only air condition that area in which the products require refrigerated temperature control. One approach to reduce the refrigeration energy demand is to house the product in localized product cooling systems. In this study, localized product cooling systems are analyzed in order to identify the saving potentials associated with a localized HVAC refrigeration system. Experimental systems were built and evaluated. The simulation analysis highlighted that smaller localized refrigeration housing can reduce total energy demand by up to 65%.

Optimal energy supply structures for industrial sites in different countries considering energy transitions: A cheese factory case study

This present study focuses on analysing the most efficient utility energy supply structure in terms of primary energy efficiency, carbon emissions and energy costs. In the German dairy industry, separate conversion with gas fired steam boiler, and cooling with ammonia chillers are the-state-of-the-art technologies. It is attractive due to its robustness and low investment costs. But given the ongoing energy transition to renewable energy, opportunities to reduce emissions will become increasingly important. There are other energy supply options, such as Combined Heat and Power (CHP) and Heat Pumps (HP), that if implemented need to compete against the conventional energy supply systems. One option is CHP to provide cogenerated electricity and heat while cooling remains supplied by ammonia chillers. In countries with high electricity Grid Emissions Factors (GEF) such as Germany and the USA, the use of decentralised CHP results in savings of primary energy and emissions. However, this option is less attractive for countries with low GEF such as France and Norway, and for places like Germany where the energy transition lowering its GEF by 50 % in 2030. In these cases, HP solutions provide the lowest emissions and highest primary energy efficiency.

Energy Efficiency Measures for Batch Retort Sterilization in the Food Processing Industry

The purpose of this study is to highlight the energy saving potentials of a batch retort sterilization process operated by steam and to develop concepts for improving its energy efficiency. By using the methodical approach of the Onion Diagram and the recovery of low grade heat sources, four comprehensive improved energy efficiency concepts have been developed. Two concepts increase the initial product temperature resulting in lower transient steam consumption rates and a decreased energy demand. The other two options transform the waste heat and the energy for product cooling into heat streams for supplying nearby heat sinks or other processes in the plant. Results show that the total energy demand can be reduced by more than 23 % and 42 % of the energy injected into the system can be recovered. The scope of the study focused on a single, independent retort to ensure the transferability of the concepts. This study also shows, using a practical example, the importance of a comprehensive process understanding and analysis prior to application of Pinch Analysis, which is needed to ensure that the correct waste heat stream temperatures are defined, necessary processing constraints are appreciated, and all possible heat sinks in the process are considered.

Hybrid-heating-systems for Optimized Integration of Low-temperature-heat and Renewable Energy

The food and beverage industries are significant industrial producers of green-house gas (GHG) emissions. Reductions can be achieved by increased energy efficiency and the use of renewable energy to replace fossil fuel use. The main efficiency method within this industries is the use of low temperature heat (LTH), i.e. below 100 °C. Sources for LTH include heat recovery from process flows, heat rejection from utility operations (i.e. chillers, combined heat and power (CHP), condensing economisers), and renewable energy (i.e. solar thermal). A hybrid heating system (HS) has been developed that can retrofit steam heater designs for the integration of LTH. Two different systems have been found, for adapting direct and indirect steam heaters, either installing an extra hot water heater or using the indirect hot water loop for the integration. In both systems the existing steam heater remains a part of the system for individual back-up. The set-up and the control algorithm of the HS allow installing a 37 % smaller hot water grid than a common design with one central back-up heater. Investigations using a comprehensive model of a whey separation and drying plant showed that implementing a piston engine CHP unit combined with the HS reduce the energy costs by 42 % and the GHG emissions by 33 %.

Comparison of Mixed and Stratified Ventilation Systems in Production Areas: Experimental and Simulation Studies

Ventilation system can have significant influences on the energy consumption, especially in factories with high thermal loads. To remove generated thermal and mass loads from manufacturing areas, several mechanisms can be applied: mixing and layering ventilation.This paper shows experimental studies to compare mixed and stratified ventilation systems for industrial buildings. These experiments were conducted in a factory model with a scale of 1:2.5. The measurements consist of vertical distribution of carbon dioxide concentration and temperature in the ambient room. Additionally, a simulation study was conducted based on the same factory model to predict the annual energy demand of mixed and stratified ventilation systems in different climatic regions. The simulation models were validated with measurements from machines and devices in the authors’ laboratories and in the factories of project partners.The results show advantages in airflow, air quality, cooling capacity and energy demand at different climatic zones when using stratified ventilation.Copyright

Simulation von Maschinen und Anlagen als thermische Lasten in der Produktion

Kurzfassung Betriebe schalten Produktionsmaschinen häufig über das Wochenende aus. Pünktlich zum Schichtbeginn müssen die abgekühlten Maschinen wieder auf Betriebstemperatur gebracht werden, wodurch hohe Energiekosten entstehen [1]. Der Beitrag illustriert anhand der thermischen Modellierung einer Produktion vielfältige Einsatzmöglichkeiten von dynamischen Simulationswerkzeugen zur Reduzierung des Primärenergiebedarfs.

Model for Estimating Load Shifting Potential

Contains the excel model used to estimate potential for load shifting. Commercially sensitive data has been redacted

Localized Climatisation of Perishable Products: Solutions for Increasing Energy Efficiency

Many industries have significant requirements regarding temperature control, air humidity and air pollution which must be strictly adhered to avoid bacterial formation and contamination. High refrigeration specifications are only required in certain areas. However, these specifications are often applied across the whole production hall which results in unnecessarily high energy demand and usage. A more energy efficient approach is the localized cooling of the product, which conditions the direct environment of the product only. This leads to the consideration of separating or localizing the products specifically requiring refrigeration in the production hall. In this paper, localized product cooling systems are analyzed in order to identify the savings potential associated with a localized refrigeration system. The study shows the energy savings potential for a manufacturing company located in three different locations: in Germany, Canada and the USA.Copyright