Field test of absorption cooling technology for trigeneration systems
|Project plan||In accordance with the objectives of field testing – adapting the laboratory plants to applications and demonstrating what thermally driven cooling systems and heat pumps can achieve – 15 locations in eight German Federal States with a wide range of cooling uses were selected at the start of the project. The implementation phase started in 2013. The first field test installations were commissioned in the summer of 2014, and the final installations are to be completed in spring 2015. The focus will subsequently be on optimising the plant technology in operation, and determining meaningful performance indicators for energy-related and economic benchmarks.|
|Developer, organizer||AGFW e.V., Bundesindustrieverband Technische Gebäudeausrüstung e.V. BTGA, TU Berlin, TU Dresden|
Initial situation, objective
In building air conditioning, more and more cooling systems are being used in Germany and worldwide. While air conditioning was previously often viewed as an added comfort at most, it is becoming increasingly common in the commercial sector due to stricter health and safety requirements and new building designs with translucent facades. In the hospitality industry, air conditioned event rooms and restaurants are often considered essential for economic success. Due to the high level of technical equipment, hygienic requirements and workstation regulations, more and more installations rooms, computer centres and production facilities are cooled. Given the European climate protection obligations and the EU’s high dependency on energy imports, new, energy-efficient technologies are required to meet the growing demand. Absorption cooling based on combined heat and power generation (CHP), waste heat use or solar thermal energy will play an important part in this.
Using absorption cooling systems driven by heat from CHP plants makes a reduction of the electricity and energy consumption possible, increasing the efficiency of the energy supply. In addition to this, the electricity generated via CHP increases in summer when cooling is generated using district and local heating instead of electricity as the energy source. Compared with the annual average of approx. 11% CHP electricity, the production currently drops to approx. 5% in summer. The thermally-driven refrigeration technology can therefore help replace less energy-efficient electricity generation (condensation power stations), and thus contribute to saving energy and reducing emissions. It also reduces further expansion of less sustainable, compression-based, electrically-operated systems.
In order to reach these goals, multiple factors must be taken into consideration. Cooling systems based on absorption cooling are more complex than systems with the compression cooling which dominate the market for planners, building developers and decision-makers. Even planners and plant manufacturers with significant experience in the latest cooling technology can make errors when applying it to absorption cooling technology. If we also consider that absorption cooling systems run at partial load can increase their secondary energy efficiency many times over with good system planning (in particular in terms of electricity consumption), planners and building developers are facing a new challenge: optimising compression cooling systems.
Work programme, implementation
Modern absorption cooling systems can be used in a wide range of applications to provide cooling. Together with AGFW, TU Berlin motivated and chose the field test partners. A diagram shows the number of functional prototypes and their total output in the field test installations used in the project broken down by air conditioning cooling, laboratory and process cooling, computer centre cooling and hospital cooling. The cooling capacity distribution diagram shows a deeper insight into the cooling technology requirements. The complete range of cooling provision above 0 °C is served, and cold water temperatures from 6 °C to 16 °C are represented over all power classes. The locations of the properties are marked with dots on the map of Germany. Besides the conurbations of Berlin and North Rhine-Westphalia, there is an even distribution between Hamburg and Rosenheim. The Karlsruhe location in the Upper Rhine Graben is assumed to offer the greatest challenges in Germany for absorption cooling technology in conjunction with dry recooling, as it operates at high cooling water temperatures and under difficult ambient conditions.
In the planning and installation phase (2013-2015), the field partners, which are generally the subsequent operators of the plants, were supported by TU Berlin in design, hydraulic planning and definition of the future operating modes. As a rule, the field test partner commissions a specialist planner with the project implementation steps in preparation for construction, who in turn clarifies the technical implementation details with TU Berlin. In its work, TU Berlin is supported at the end of the respective planning step by TU Dresden and ILK Dresden. Before the work is tendered, the monitoring concept is drawn up including all measurement points. This concept must not only permit the evaluation of the absorption cooling systems and optimisation during operation (both TU Berlin) at a later stage of the project, but is also intended for model validation of simulating trigeneration systems (TU Dresden) and evaluation of energy and economy (TU Berlin/TU Dresden). For this purpose, up to 1,000 control signals, temperatures, pressures and heat volumes were recorded in individual properties, saved and provided for evaluation.
In 2014, the commissioning will take place for initial field tests. These field tests will then transition to the operation/evaluation and optimisation phases, which can take one to three years depending on the field test, and will be replaced by a “pure” operation and evaluation phase. AGFW and BTGA will be the scientific partners in all project phases, but will also support the field test partners and their contractors at their request, and evaluate the technology feedback for energy supply companies and plant manufacturers and installers, and will use the results as part of their association work.