Challenges and opportunities for carbon neutrality in China’s building sector—Modelling and data

A novel approach of day-ahead cooling load prediction and optimal control for ice-based thermal energy storage (TES) system in commercial buildings

Effect of boron on microstructure and its influence on elevated temperature properties of titanium stabilized AISI 321 steel was studied. A comparative study on mechanical properties of AISI 321 steels with and without boron addition is done. Both steels were worked to get appropriate reduction using forging-rolling process followed by solution annealing (SA) and stabilizing treatment (ST) at the appropriate temperature. Optical micrographs revealed uniform distribution of precipitates in steel. The precipitate count for Ti-stabilized AISI 321 steel with 30 ppm boron (TB30) was higher than Ti-stabilized AISI 321 steel (TB1) in which TiN and TiCN precipitates were observed. In addition to this, for TB30 steel containing boron precipitates of Fe2B and Cr2B were also observed. Precipitates refined the austenite matrix and provided yield strength stability to the AISI 321 steels. Boron addition in TB30 steel improved YS and UTS of AISI 321 steel with a marginal loss in ductility. SA and ST, TB30 steel exhibited best mechanical properties at room and elevated temperature (350 °C). Further, quantification of intergranular corrosion was done by sensitization of samples at 675⁰C for one hour and evaluated as per ASTM A262 specification practice A and practice E. Addition of nearly 30 PPM boron is highly beneficial in titanium stabilized AISI 321 steel that led to increased resistance to sensitization (both according to practice A and practice E) and improved the microstructural stability at elevated temperature resulting a reduction in intergranular corrosion and improved the elevated temperature mechanical properties. Thus, SA and ST, TB30 steels showed superior results as compared to TB1 steel. Study shows that TB30 steel is more suitable material to replace the cooling water inlet and outlet tubes of VVER type nuclear reactor.

Effect of heat treatment on microstructure and mechanical properties of boron containing Ti-Stabilized AISI-321 steel for nuclear power plant application

Commercial prototype building models were developed by the United States Department of Energy (DOE) to analyze the energy savings of the ASHRAE 90.1 standard. However, in the DOE models, occupant behavior inputs were deterministic and the stochasticity of occupant behavior was not fully characterized. This study evaluated the impacts of stochastic occupant behavior on building energy consumption and energy savings analysis from upgrading the ASHRAE 90.1-2016 to 2019 in sixteen climate zones in the United States (U.S.). Three occupant behavior styles (austerity, normal, and wasteful) were defined to represent the different levels of energy consciousness. The DOE medium office prototype models were used as the baseline (normal behavior style). The occupant behavior functional mock-up unit (obFMU) was used to model the stochastic occupant behavior models (austerity and wasteful). The EnergyPlus medium office prototype models were modified to co-simulate with the obFMU models. The results of 16 climate zones were aggregated by the relative construction volume of each climate zone. The results showed that the weighted national annual source energy use intensity (EUI) of the austerity, normal, and wasteful behavior styles were 203.81 kWh/m2, 287.15 kWh/m2, and 388.33 kWh/m2 for ASHRAE 90.1-2016, and 192.43 kWh/m2, 273.48 kWh/m2, and 371.28 kWh/m2 for ASHRAE 90.1-2019, respectively. Compared to the normal behavior style, the austerity behavior style consumed 29% less source energy, while the wasteful behavior style consumed 36% more source energy. From upgrading the ASHRAE 90.1-2016 to 2019, the energy saving percentages based on the austerity, normal, and wasteful behavior styles were 5.59%, 4.78%, and 4.42%, respectively. The stochastic occupant behavior significantly impacted the building energy consumption, and their impacts on the energy savings analysis of upgrading ASHRAE 90.1 were also not negligible.

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Impacts of Occupant Behavior on Building Energy Consumption and Energy Savings Analysis of Upgrading ASHRAE 90.1 Energy Efficiency Standards

Impacts of uncertainty in building envelope thermal transmittance on heating/cooling demand in the urban context

Buildings contribute to almost 30% of total energy consumption worldwide. Developing building energy modeling programs is of great significance for lifecycle building performance assessment and optimization. Advances in novel building technologies, the requirements of high-performance computation, and the demands for multi-objective models have brought new challenges for building energy modeling software and platforms. To meet the increasing simulation demands, DeST 3.0, a new-generation building performance simulation platform, was developed and released. The structure of DeST 3.0 incorporates four simulation engines, including building analysis and simulation (BAS) engine, HVAC system engine, combined plant simulation (CPS) engine, and energy system (ES) engine, connected by air loop and water loop balancing iterations. DeST 3.0 offers numerous new simulation features, such as advanced simulation modules for building envelopes, occupant behavior and energy systems, cross-platform and compatible simulation kernel, FMI/FMU-based co-simulation functionalities, and high-performance parallel simulation architecture. DeST 3.0 has been thoroughly evaluated and validated using code verification, inter-program comparison, and case-study calibration. DeST 3.0 has been applied in various aspects throughout the building lifecycle, supporting building design, operation, retrofit analysis, code appliance, technology adaptability evaluation as well as research and education. The new generation building simulation platform DeST 3.0 provides an efficient tool and comprehensive simulation platform for lifecycle building performance analysis and optimization. 

https://link.springer.com/content/pdf/10.1007/s12273-022-0909-9.pdf

DeST 3.0: A new-generation building performance simulation platform

A certain amount of Ti was added into high boron alloyed stainless steel with content 2.25%B, and then high boron alloyed stainless steel composite casting slab with three layers was fabricated , in which central layer is high boron alloyed stainless steel containing Ti and cladding is plain 304 stainless steel without Ti. The microstructure of core and interface and the mechanical property of the composite plate were studied after hot forged, hot rolled and solution treated process respectively. The results show that the boride in as-cast microstructure of core are (Fe,Cr)2B phase with long strip and TiB2 phase with petal shape, moreover the formation of TiB2 phase decreases the amount of (Fe,Cr)2B phase. Two kinds of boride are fully broken after hot rolling and distributed in the form of block uniformly in matrix, and TiB2 phase is more fine uniform. The mechanical property especially plastic performance of high boron alloyed stainless steel composite plate containing Ti after solution treatment is improved significantly, it has reached and surpassed the United States ASTM A887-89 delivery standards.

Study on Microstructure and Property of High Boron Alloyed Stainless Steel Composite Plate Containing Titanium

High boron alloyed stainless steel composite plates with different Ti content by cladding casting and hot forming process were fabricated. The mechanical properties of composite plates were analyzed after solution treatment. The results show that the composite plate has optimal microstructure and properties at 1100°C solution temperature, holding for 4h.The comprehensive properties of the composite plates are improved with the increase of Ti content, but excess Ti content can lower the plasticity. The elongation and the tensile strength of composite plate reaches 29% and 527MPa respectively, the mechanical properties can meet and exceed the supply standard requirements in ASTM A887-89 of U.S. when the reasonable content of Titanium is about 5%.

Yan Long Liu

Papers

DeST 3.0: A new-generation building performance simulation platform

Study on Microstructure and Property of High Boron Alloyed Stainless Steel Composite Plate Containing Titanium

Research on Mechanical Properties of High Boron Alloyed Stainless Steel Composite Plate Containing Titanium