Investigating the dynamics of recombinant protein secretion from a microalgal host

Lauersen KJ, Huber I, Wichmann J, et al. Investigating the dynamics of recombinant protein secretion from a microalgal host. Journal of Biotechnology. 2015;215:62-71

Pipe internal recirculation in storage connections - Characteristics and influencing parameters

Pipe internal recirculation (PIR) is an undesired phenomenon which may lead to significant additional heat losses. Although different research institutes already measured singular PIR effects, there is still a lack of wide-ranging evaluations and practical solutions. This paper describes a test and evaluation method and reports on results regarding the influence of the pipe's slope, the material (copper, stainless steel) and diameter on the PIR caused heat loss coefficient. For combined pipe path arrangements a new method is presented, which allows to calculate the heat losses from basic investigations on horizontal and vertical pipe orientations. This method has been experimentally validated. Finally, the effectiveness of different measures for the reduction of PIR induced heat losses is presented

Optimal Connection of Heat Pump and Solar Buffer Storage under Different Boundary Conditions

The paper presents the results of a simulation study, in which the connection of heat pumps and buffer storage tanks has been investigated. The simulations are carried out for a new type of a solar thermal combi system with a 32 m2 collector field leading to a solar fraction of more than 50%. In the first stage, the most influencing installation and operation parameters have been identified and optimized for typical boundary conditions of weather/climate, hot water demand, building and space heating system. Within further simulations these boundary conditions are varied to find generalized design rules for the connection of heat pumps and storage tanks. These results are presented and discussed

Pipe internal recirculation in storage connections - An unseen efficiency barrier

Basically, pipe internal recirculation (PIR) at storage connections is a known phenomenon. However, it is not sufficiently considered by storage manufacturers and installers. There is still a lack of awareness and quantification of the PIR effect in typical installations and practice-oriented solutions. Within this paper, the final results of a research project aiming at the detailed qualitative description and quantification of the effect including extrapolation of the results regarding the PIR impact on storage heat losses are presented. This includes the results regarding the influence of the pipe's material (copper, stainless steel, plastic), diameter, insulation and connection type (direct to storage, indirect via immersed or external heat exchanger) on PIR including their effects on the overall heat losses of ready installed storage tanks. Derived from generalized measurements, a calculation method has been developed, which enables to determine the annual heat losses caused by PIR in domestic hot water storages using dynamic system simulations (TRNSYS). In conclusion, different measures for the reduction of PIR induced heat losses and their effectiveness may be presented. © 2015 The Authors

Thermal storage tanks in high efficiency heat pump systems - Optimized installation and operation parameters

Heat pumps have a significant and increasing share in the European heating market. In most applications heat pumps are operated with a storage tank, either for domestic hot water or for the space heating circuit. The design of the storage and its connection to the heat pump has a significant influence on the performance of the heat pump and the whole system. Within a comprehensive investigation, system simulations in TRNSYS are used to identify the optimum design of two typical systems with a heat pump connected to a buffer storage including total storage volume, number and size of heated zones, sensor and in- and outlet positions. As result, a sharp decrease in the energy demand can be reached if the storage is equipped with two heat zones instead of one. This can be explained by the decreased set temperature in the additional heat zone for space heating leading to a higher performance of the heat pump. Other measures with a positive effect on the energy demand are a large space heating volume, the number and place of sensors, low set temperatures and the sensor position in the upper part of the heating zone. The investigation gives important recommendations how to connect a heat pump with a storage tank and may be considered as design rules for all heating systems consisting of heat pump and different types of storage tanks

Simulation and Evaluation of Solar Thermal Combi Systems with Direct Integration of Solar Heat into the Space Heating Loop

Usually, solar heat in combi systems is used via a buffer storage. In contrast to that, the solar collectors may be connected directly to the space heating circuit in order to store the heat in the building itself. Such a direct solar integration is investigated within system simulations for different layouts and heating elements. The simulations show significant reductions in the final energy demand as well as an increasing solar yield due to less thermal losses of the storage tank compared to the usual solution with one buffer storage. A prototype of one of the investigated heating concepts within a single family house proofs the functionality of the system concept and the high solar yield, particularly at low radiation levels. Since only a few manufacturers provide such system solutions with a direct solar integration, the results may have an important impact on the future development of combi systems

Solar active building with directly heated concrete floor slabs

A new concept for solar active houses is presented within this paper. In contrast to existing solar house solutions, the solar collector heat gains are distributed in a temperature-optimized way to three different heat sinks - a significantly smaller storage tank, concrete floor elements directly fed by the solar circuit and a ground heat exchanger which also serves as the heat source of a heat pump, which is the backup heater. This new layout should reduce the today's usual extra system costs of solar houses by about 25%. System simulations prove the functionality of the concept and show even higher solar fractions and energy savings as simulated for the existing solar active house concept. One of the main components in the new concept is the controller which has to decide which heat sink will be charged. A control strategy was developed which evaluates the potential outputs of the collector operating to each heat sink. Simulations allow determining the optimal control parameters for this approach. While the thermal activation is able to compensate the decreasing solar input to the smaller storage tank, the effects of the regeneration of the ground heat exchanger are significantly smaller. However, the regeneration avoids a long-term temperature decrease in the ground and may allow a reduction of the heat exchanger area