Building systems and indoor environment : simulation for design decision support

This paper outlines the state-of-the-art in integrated building simulation for design support. The ESP-r system is used as an example where integrated simulation is a core philosophy behind the development. The paper finishes with indicating a number of barriers, which hinder routine application of simulation for building design

Integrated simulation for (sustainable) building design : state-of-the-art illustration

Many buildings are still constructed or remodelled without consideration of energy conserving strategies or other sustainability aspects. To provide substantial improvements in energy consumption and comfort levels, there is a need to treat buildings as complete optimised entities not as the sum of a number of separately optimised components

Application of new measurement techniques and strategies to measure ammonia emissions from agricultural activities

Agriculture is the main contributor to the ammonia emissions in the Netherlands. In order to comply with the ammonia emission reduction assigned to the Netherlands, new techniques have been implemented to reduce the ammonia emissions from animal houses, and after application of slurry into the field

Application of large underground seasonal thermal energy storage in district heating system: A model-based energy performance assessment of a pilot system in Chifeng, China

Seasonal thermal energy storage (STES) technology is a proven solution to resolve the seasonal discrepancy between heating energy generation from renewables and building heating demands. This research focuses on the performance assessment of district heating (DH) systems powered by low-grade energy sources with large-scale, high temperature underground STES technology. A pilot DH system, located in Chifeng, China that integrates a 0.5 million m3 borehole thermal energy storage system, an on-site solar thermal plant and excess heat from a copper plant is presented. The research in this paper adopts a model-based approach using Modelica to analyze the energy performance of the STES for two district heating system configurations. Several performance indicators such as the extraction heat, the injection heat and the storage coefficient are selected to assess the STES system performance. Results show that a lower STES discharge temperature leads to a better energy performance. A sensitivity analysis of the site properties illustrates that the thermal conductivity of soil is the most influential parameter on the STES system performance. The long-term performance of the STES is also discussed and a shorter stabilization time between one and two years could be achieved by discharging the STES at a lower temperature.This research is part of the seasonal storage for solar and industrial waste heat utilization for urban district heating project funded by the Joint Scientific Thematic Research Programme (JSTP)–Smart Energy in Smart Cities. We gratefully acknowledge the financial support from the Netherlands Organisation for Scientific Research (NWO). We would also like to thank our research partners from Tsinghua University working on the project of the International S&T Cooperation Programof China (ISTCP) (project No. 2015DFG62410). Without their efforts, we would not have been able to obtain the technical data to conduct the case study

Accuracy in evaluation of view factors between small and far surfaces

The contribution describes an approach that can be used during evaluation of a view factor between complex emitter and planar absorber surfaces. Rather than sophisticated mathematical attitude, practical way is offered. The source surface is divided into smaller parts with same surface normal and using some minor assumptions, summary view factor is calculated. The contribution is aimed on an error that can be caused considering these assumptions and further on, on a case study (evaluation of a view factor between ceramic plaques source surface and a photometric sensor), real differences are shown

On the relation between shape and downward radiation of overhead radiant heaters

The paper aims on evaluating and assessing of the influence of a shape of overhead luminous infrared heater’s burner on heat distribution to the ambient. These devices are mainly used for heating of industrial or other large space buildings. The contribution is based on comparison between the experimental results and created mathematical model. The latest experimental results show that the maximum of radiant intensity does not lay right below the radiant heater. Actually, there exists a ring of maximal values around heater’s midpoint axis. Results prove that instead of reflectors’ geometry, very complicated shape of gas luminous heater’s burner plays the most significant role in radiant heat transfer from the luminous heater. It was evaluated that the position of the radiant intensity maximum is around 10° from the radiating surface’s normal direction. All the findings can be summarized in conclusion that uniform distribution of radiant intensity required for thermal comfort of occupants can be maintained just by optimizing of the shape of radiant heater’s burner. Besides this conclusion, it is also apparent that adding the reflector actually increases summary radiant heat flux to the desired zone and therefore radiant efficiency increases. It is also clear that varying the reflector shape, different improvement of the efficiency can be expected

Free-energy functional for freezing transitions: Hard sphere systems freezing into crystalline and amorphous structures

A free-energy functional that contains both the symmetry conserved and symmetry broken parts of the direct pair correlation function has been used to investigate the freezing of a system of hard spheres into crystalline and amorphous structures. The freezing parameters for fluid-crystal transition have been found to be in very good agreement with the results found from simulations. We considered amorphous structures found from the molecular dynamics simulations at packing fractions $\eta$ lower than the glass close packing fraction $\eta_{J}$ and investigated their stability compared to that of a homogeneous fluid. The existence of free-energy minimum corresponding to a density distribution of overlapping Gaussians centered around an amorphous lattice depicts the deeply supercooled state with a heterogeneous density profile

Design optimization study for an infrared heater using CFD and sensitivity analysis

Sensitivity analysis (SA) has become a very popular technique for various application areas. However, not many studies concern SA using CFD (computational fluid dynamics). The main problem appears to be the large number of model executions when using the Monte Carlo method of SA. The computing resources and time needed for such a SA in combination with CFD (in which one model execution could take several hours) can be enormous. Nevertheless, this paper describes an approach of using SA in such cases. The recommendations are obvious: simplifying the model as much as possible; considering just a key part of the model; and take more care about the speed of convergence. On this basis a case study on "Optimization of gas infrared heater radiation geometry" has been performed. The most interesting result is that the shape of the heater and the reflector material do not significantly influence the heat delivery to the occupied zone. The main conclusion is that Monte Carlo sensitivity analysis is not suitable for large CFD models with low level of abstraction. In order to obtain good results, we recommend to select a smaller part of the overall domain and/or to significantly simplify it