Abstract

The aim of the study was to utilize building data for prediction of development in energy use of a typical building type. In this study, energy use and its future development for kindergartens in Trondheim, Norway, were analyzed. The total area of all the kindergartens was about 76 000 m2 , where the area of each kindergarten was ranging from 100-4 471 m2 . The kindergartens were divided into two cohorts based on their connection to district heating (DH). Typical heat and electricity duration curves per m2 of each cohort within six years were identified. The average total annual energy use was 177 kWh/m2 for kindergartens without DH, and 168 kWh/m2 for the ones connected to DH. The peak load values were similar for both cohorts, about 140 W/m2 . Analysis of the duration curves showed a bigger electricity load variation for the kindergartens without DH. Among the building cohort with DH, three cases were found depending on the energy share from DH; i.e. DH high share, DH average share, and DH low share. By following different background data for CO2 factors of electricity and local DH, the kindergarten with DH high share has almost the lowest annual CO2 emission. Finally, a prediction was made by assuming 14.2 % growth rate of kindergartens on the ground of the average 6-year total kindergarten area. The result showed that if more than 50-67 % of the new building area would be connected to DH, a smaller increase of CO2 emission from the predicted area could be achieved. This proved that buildings with DH were more robust than the ones without DH concerning CO2 emission. The suggested analysis method and identified duration curves could be used to as a reference example.

Abstract

Due to climate change, global average outdoor temperatures are expected to further increase, modifying the energy demand of the buildings from today. As new buildings are constructed to last, the impact of climate change should be taken into account during the design phase. The objective of this study is to investigate the changes in total and peak energy demands in buildings having different levels of thermal insulation, to explore if the impacts of climate change are similar to all selected building types by 2050. The impact of climate change to the weather data is gathered from different climate change projections to achieve a comprehensive analysis of the possible future directions. The new weather files are created using ‘morphing’ method and using meteorological test reference year for building simulation and measured weather data for constructing the future weather files. The results indicate that the energy demand will decrease by 6-12% in passive building types by 2050, with heating demand decreasing 6-13% and by starting to have cooling demand in A1B, A2 and RCP8.5 scenarios for passive building. The scenarios with higher projections for temperature increase also have larger decreases in total energy demands indicating that the starting of having cooling demand does not overcome the decrease in heating demand. Moreover, the peak demand for heating is projected to decrease in the future but, at the same time, peak cooling demand starts to occur, which may need to be considered in the future energy system constraints.

Abstract

Driven by climate change concerns, our energy system has been under steady change. Renewable energy sources are increasingly used to decarbonize our energy system, making it also more decentralized. At the same time, information and communications technologies (ICT) are enabling smart services for consumers, offering financial benefits through demand side management (DSM) programs. This study investigates various DSM solutions for a detached house in Northern Finnish conditions in 2050. A thermal model is used to model the thermal behavior of the building and test out DSM programs in direct electric space heating and underfloor heating alternatives. The 2050 scenarios are created from climate change projections, existing data on electricity generation and from projections on the future energy system and cost of electricity. The results indicate that load shifting with photovoltaic (PV) generation is a potential way of reducing costs and CO2 emissions both today and in 2050, but it lacks economic feasibility due to long payback times of the investments. Cost optimized direct electric space heating and underfloor heating are both able to provide economic and environmental benefits when compared to manually controlled heating. The scenarios presented in the paper suggest that 95-96% emission reduction can be achieved; however, the electricity cost of households is expected to increase by 174-253%. At the same time electricity consumption from the grid is expected to reduce by 3- 10% in all the scenarios.

Abstract

This article aims to model the transmission architecture of a planetary power split Hybrid Electric Vehicle (HEV) to improve fuel efficiency as well as to reduce emission, conforming sustainable design. The model is developed using model based equations, retrieved from literature and Design of Experiment with response surface solution mode. Development of power management strategy for the above, utilizing associated mathematical modeling of the proposed gearset topology guided transmission architecture is disseminated in this work. Design solution for suitable gearset topology is derived by utilizing response surface method and genetic algorithm. The result shows that connection between planetary gear stages, amongst considered variables, holds highest significance and also helps to infer that most suitable configuration is to couple the engine with the second planet carrier for a two-stage power split device. The modelling-based result depicts successful implementation of two stage planetary gear train as power split device with fossil fuel consumption reduction of 49.16%, maximizing electric power utilization for greener transportation.

Abstract

Static synchronous compensator (STATCOM) can effectively improve the power quality in the mediumvoltage distributed energy system (DES). In order to keep the system stable operation, fault-tolerant ability should be maintained to improve the reliability of STATCOM. With the idea of virtual capacitor voltage, a simplified fault-tolerant control scheme is proposed for popular cascaded H-bridge (CHB) based STATCOM. First, an improved modulation method is adopted to significantly reduce these carrier waves. Then, based on the virtual capacitor voltage, the control scheme during the cell fault can be further simplified. Finally, the detailed postfault operation principle is presented according to different operation conditions of STATCOM, where the capacitor voltages in the faulty phase can remain unchanged in certain cases. Validation results verify the effectiveness of the proposed fault-tolerant scheme.

Abstract

The purpose of this study is to understand the effect of an over-estimated cooling set-point temperature (28°C) on work productivity in Korea’s public buildings during the summer season. Two experiments were conducted. The first experiment aimed at measuring work performance through typing and cognitive tests and detecting work stress using an electroencephalogram at 28°C. The second experiment was conducted at 24°C with the same contents as the first. The results showed that a cooling set-point temperature of “28°C” brings benefits in terms of energy consumption, but it drops work performance, thereby having an adverse effect on overall productivity.

Abstract

A DC current sensor for electric vehicle charging billing is designed by using the magnetic modulation scheme of the duty cycle model. Based on the analysis of the working principle of the sensor, the mathematical model of the sensor is given by analytical method. The design principles of the core, coil and circuit parameters are analyzed, and the prototype of the DC current sensor is fabricated and tested. The test results show that the sensor has high measurement accuracy and good stability. Due to the full digital design, the measurement circuit is less interfered by the external electromagnetic environment, suitable in places with complex electromagnetic environment such as new energy vehicle charging piles.

Abstract

This paper aims to study the solar thermal performance of a novel solar micro-channel loop heat pipe-PV/T system on experimental stage based on the height difference between the PV/evaporator and condenser, including the impact of the height difference on the temperature distribution of PV panel, solar thermal efficiency. It is found that (1) when the system become steady, the PV module surface temperature is almost decreases with the rise of the height difference; (2) The aluminium (Al) plate in the mid-layer achieved a little higher temperature compared to the PV surface and micro-channel wall which were above and below the Al plate respectively; (3) the solar thermal efficiency of the novel PV/T-MCLHP system varied with the height difference between the heat exchanger and the evaporator; (4)During the specific operational process, solar thermal efficiency of the system increased from 48.85% to 57.13% while the height difference increased from 0.7 m to 1.3m. And 1.1m is finally taken as the optimal value of height difference. The results of this experiment can help to optimize the system construction and thus help to develop a high thermal performance and low cost solar PV/T system for the space heating.

Abstract

The high temperature slag discharged from metallurgical industry has the characteristics of high temperature and large discharge. In 2017, the total amount of liquid slag produced by the world iron and steel industry is about 913 million tons and the amount of waste heat resources contained in liquid slag is equivalent to about 38 million tons of oil equivalent. It has great value of waste heat recovery and resource utilization. Among all kinds of slag treatment methods, dry centrifugal granulation has the advantages of small particle size and high vitrification, which is a developmental slag treatment process. The slag particles produced by centrifugal granulation are typical semimelt and wide-screening particles. This paper reviews the current status of basic scientific research of gas-solid heat transfer, solid-solid heat transfer and phase evolution of semi-melt particles by scholars all over the world. On this basis, in order to achieve efficient waste heat recovery and resource utilization of centrifugal granulated blast furnace slag particles, this paper puts forward specific research contents and technical development ideas about the heat transfer mechanism of semi-melt and wide-screening particles and the hightemperature waste heat recovery technology of hightemperature slag particles.

Abstract

In a power plant, combustion condition monitoring is essential for maintaining stable operations and operational safety. Therefore, it is crucial to develop an intelligent combustion condition monitoring method. Existing methods not only need a large quantity of labeled data but also lack of generalization ability for monitoring the new condition. Aiming these problems, the present study presents a novel approach combining denoising autoencoder (DAE) and generative adversarial network (GAN) to monitor combustion condition. With the aid of the learning mechanism of the GAN, the learning ability is improved to learn representative features. These learned features are then fed into the Gaussian process classifier (GPC) for condition identification. Furthermore, new conditions can correctly be classified by simply retraining the established GPC using a small amount of labeled data under the new conditions, rather than training from scratch. Experiments were performed on a gaseous combustor and results indicate that the proposed approach can extract representative features accurately and provides higher accuracy for condition identification such as 99.4% for original conditions and 99.5% for the new conditions.