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Abstract It is state of technology in district heating systems to use sand as backfill material for district heating pipes (DHP). In conventional pipeline construction, Temporarily Flowable Backfill Materials (TFB) have been already used for backfilling the pipe zone. TFB consists of the excavated material, cement, water and optionally bentonite. Environmental and economic advantages are that the excavated material can be reused and that TFB requires no compaction. In order to embed district heating pipes in TFB, soil mechanical parameters of the TFB are required. Above all the resistance to temperature-induced axial displacement should be well-known in order to estimate the displacements of the DHP, as well as the stress distribution along the DHP. Compared to sand as a non-cohesive backfill TFB have remarkable adhesive contact stresses which result in considerable resistance forces. In this article, the contact behavior between TFB and DHP is described as well as the effect on the DHP statics. Therefore, the results of various laboratory tests are summarized and presented to understand the interface-resistance-characteristics (IRC) of the DHP/ TFB interface. Then, the deduced IRC was implemented in a computer program for some comparative calculations with sand and TFB. Finally, the results of cyclic loading are presented and discussed.

Swirl combustors have proven as effective flame stabilisers over a wide range of operation conditions thanks to the formation of well-known swirl coherent structures. However, employment of swirl combustors to work on lean premixed combustion modes while introducing alternative fuels such as high hydrogen blends result in many combustion instabilities. Under these conditions, flame flashback has been considered as one of the major instability problems that have the potential of causing considerable damages of the combustion systems hardware in addition to the significant increase in pollutant levels. Combustion Induced Vortex Breakdown (CIVB) is considered a very particular mode of flashback mechanism in swirling flows as this type of flashback occurs even when the fresh mixture’s velocity is higher than the flame speed, consequence of the interaction between swirl structures and swirl burner geometries. Improvements of burner geometries and manipulation of swirl flows can produce good resistance against this type of flashback. However, increase flame flashback resistance against CIVB can lead to an increase in the propensity of another flashback mechanism, Boundary Layer Flashback (BLF). Thus this paper presents an experimental and numerical approach that allows the increase in CIVB resistance by using diffusive air injection and simultaneously avoid BLF by changing the wall boundary layer characteristics using microsurface grids as a liner for the nozzle wall. Results show that using those two techniques together has promising potentials regarding wider stable operation for swirl combustors, enabling them to burn a great variety of fuel blends safely.

Power generation from the renewable energy sources is usually intermittent and uncontrollable which challenges the grid frequency stability. The smart control of loads is an effective means to mitigate the challenge. A decentralized control of heating loads -- industrial melting pots (MPs), was developed which dynamically changes the power consumption of loads in response to grid frequency. A thermodynamic model of MPs was developed and validated based on site measurements by Open Energi. An aggregation of MP models with the control was integrated with a simplified Great Britain power system model. Results showed that MPs are able to provide frequency response in a way similar to generators, which provide a means for the system operator to quantify the benefits of demand response.

AbstractAmine based solvent used for CO2 capture can be lost during the process due to: degradation, vaporization, mechanical losses and aerosol (mist) formation. Only recently, studies have appeared pointing out that aerosols can dominate the total amine emission at pilot plant scale behind coal fired power plants. Future full scale amine scrubber installations will be imposed emission limit values (ELV) for a number of components including NH3 and the amine itself. Most likely these ELV will be expressed as maximum concentrations tolerated in the CO2 poor flue gas leaving the stack so it is important to prevent or cure amine aerosol emission. The study presents a novel combination of two existing measurement techniques, that measure: (i) amine emissions from the top of the absorber using FTIR and (ii) PSD of the incoming flue gas using the ELPI+. The study is the first to show how combining these two measurement techniques allows to predict the presence or absence of mist formation. This hypothesis is based on information obtained during several measurement campaigns on different pilot plants.

Solar concepts show potentially an improved cost-performance (energy) ratio when applied as the integrated parts of building renovations. This paper reported a compact solar thermal facade (STF) module with the internally extruded flow channel suiting for solar renovation concept in buildings. A few of impact factors were considered for the parametric study in order to optimize the STF's configuration for various applications through the validated simulation model. The overall research results are expected to be useful for further improvement in the thermal performance of solar renovation measures.

“Off-the-shelf” devices have attracted much consideration lately, especially in emulsions production in droplet-based microfluidics. While many simple and cost-effective designs have been proposed and demonstrated, the functionability of these purported simple devices has been questioned, especially in emulsions generation for commercial scale. In this work, a simple needle-based device was used in the production of functional core-shell microcapsules of uniform sizes, typically in the range of 600 to 720 µm, and shell thickness of 20 to 110 µm, and C.V of 0.97 to 3.0%. These core-shell microcapsules are a new form of carbon capture materials, with carbon solvent encapsulated in thin polymeric shell. The microcapsules synthesized were subjected to absorption-desorption tests. This work has successfully demonstrated the use of off-the-shelf microdevice and its reliability for the production of functional microcapsules.

AbstractAn Artificial Neural Network surrogate modelling approach was used to optimise CO2 storage into a highly heterogeneous semi- closed saline aquifer which exhibits considerable pressure increase due to injection. The methodology was implemented to minimise the overall field pressure and well bottom-hole pressures, and to maximise the amount of dissolved and trapped CO2 in the storage aquifer. Different realisations of permeability and porosity were stochastically generated to represent the uncertainty in the model. Artificial neural networks were used to reduce the computational time of the optimisation procedure by approximating the objective functions for CO2 storage as surrogates to the expensive solutions of flow by the simulator. A multi- objective evolutionary algorithm was run on these approximators to generate solutions of the multi-objective optimisation's Pareto front. These solutions were compared with the solutions obtained by the computationally expensive optimisation and they were found to give satisfactory results, illustrating that this methodology can be a viable, and low computational cost alternative for optimisation in CO2 storage design.