Numerical and computational analyses of interface position during inward solidification of composite phase change materials (PCM) in spherical container were explored in this study. The applications of methods such as perturbation, strained coordinates and (improved) quasi-steady solution on spherical inward solidification were investigated and compared with the results of numerical simulation. The solidification positions of porous composite PCM with different porosities solved by strained coordinates and (improved) quasi-steady methods were compared when the Stefan number was 0.1. The complete solidification time was found to be rapidly shortened as the porosity decreased.
Ambitious targets were set in Sweden to increase the share of renewable energy resources and reduce greenhouse gas emissions. Renovating old detached houses can assist in achieving the abovementioned targets, since they make up a great share of the final energy consumption and carbon dioxide emissions in Sweden. Although, several attempts were taken to improve the energy performance of the detached houses, the implementation of energy efficient renovation is yet low due to mainly high investment cost. Former studies evaluated the cost effectiveness of various energy efficient renovations in renovating detached houses in Sweden, but they provided no information how possible climate futures affect the determination and adoption of energy efficiency policies, such as monetary instruments. Accordingly, this study considered three distinct energy renovation packages and analyzed the subsidies required for implementing renovation packages for given interest rates and lifetimes. Furthermore, three different climate scenarios were considered to analyze the effect of possible climate futures on subsidies required. The analyses of results show that increasing the lifetime have greater impact on required subsidies than increasing the interest rate. Furthermore, the results show that variation in future climate conditions changes the required subsidies when implementing energy efficiency renovations. Results can be used as an aid when adopting energy efficiency policies.
Detachment from the national gridline makes the remote mines in the cold climate regions of Canada solely dependent on diesel generators for power generation purposes. Notwithstanding, more than 30% of the consumed diesel by these generators is frittered away as heat through the exhaust. To endure the long harsh winters, these mines also require substantial amounts of heating which is usually provided by burning diesel or propane. In such a scenario, the installation of a diesel exhaust heat recovery system in these remote mines has been considered as a sustainable strategy to preheat the mine intake air. However, this combined heat and power generation strategy cannot provide all the necessary heating due to the daily misbalance between the heating demand and the available heat in the exhaust of the diesel generator. Coupling seasonal thermal energy storage with the waste heat recovery system is a possibility that seeks to resolve such issue. This study investigates the integration of a seasonal thermal energy storage with a diesel exhaust heat recovery system in a remote mine in northern Canada by analyzing several possible alternatives regarding capacity and rates of energy loss. The financial impact of these parameters has been added to show the viability of the proposed strategy
CO2 capture from high operating temperatures are of special interest as it is economically appealing over low temperature CO2 capture process in Post-combustion capture. This work contributes to the estimation of new and complementary density data for CO2 confined in ‘L’ shaped carbon slit pores at high temperatures and pressures. CO2 adsorption capacities in ‘L’ shaped carbon slit pores of heights 20Å, 31.6Å, 63.2Å, 94.85Å and 126.5Å at 673.15 K and 873.15 K over a pressure range of 500 kPa to 4000 kPa are predicted by Grand Canonical Monte Carlo simulations. Elementary Physical Model is employed to model CO2 at these temperatures and pressures both in bulk and confined phase. CO2 adsorption capacities and the unique structural properties of the confined CO2 at all the condition mentioned above has been estimated in presence of the wall-fluid interactions and the fluid-fluid interactions. The Steele wall potential is used to model the wall-fluid interactions inside carbon-based adsorbents that have a slit shaped geometry.
This paper presents a social, economic and environmental study on a novel solar-powered zero-bill rural house space heating system compared to the conventional coal-powered and gas-powered systems. The system can significantly reduce the fossil fuel consumption, and reach to zero-bill operation, thus decreasing the operation charge and air pollution. By using the established model, the research analyses the energy performance of the novel zero-bill solar-powered system under a typical northern China weather condition (Taiyuan city). Then, it compares the economic and environmental performances between three space heating systems. It is found that, for a 100m2 typical rural house, the total heat demand is 8081kWh during the heating season. According to the local feed-in tariff, 0.75RMB/kWh , the PV model can earn 1297.2RMB per year, which is higher than the annual system electricity bill, 732.48RMB, and thus the novel system can reach to zero-bill and zero energy consumption. When it comes to economic analysis, due to the zero-bill and zero energy consumption characteristics, the system has a cost payback period of 14.8 years and a life-cycle net cost saving of 17573RMB compared with the coalpowered system. In contrast with the gas-powered system, the system has a cost payback period of around 5.9 years and a life-cycle net cost saving of 52723RMB. Furthermore, under the view of environment, one set system can annually save 1320kg standard coal or 1022.39m3 natural gas. Besides, it also annually reduces the 897.6kg harmful dust, 3220.8kg CO2, 99kg SO2 and 49.5kg NOx compared to the most environmentally contaminated coal-powered system. The widely use of the novel solar-powered system can enormously help to improve the living standard of the residents staying in a wide range of rural areas in northern China, and thus the system can harvest greater social, environmental and economic benefits subsequently.
This study researched an efficient-utilization planning method for community buildings, which considers supply- and demand-side factors comprehensively. The method consists of three key aspects. The first is the goal orientation of renewable energy utilization planning boundary condition optimization. The second is community building function optimization based on load leveling, and the third is building morphology optimization based on the energy control. The method is an important reference for community energy planning in China.
This study presents an experimental rig of singlestage heat transformer (SSHT), to compare its performances in case of producing high-temperature water (HTW) or low-pressure steam (LPS). SSHT was built with four vertical falling film heat exchangers using a LiBr-water binary working fluid and is driven by lowgrade hot water. Bilateral falling film vertical absorber is adopted for production of HTW or LPS. Following the principle of single variable, the effects of temperature and flowrate of heating water on the useful output heat, coefficient of performance (COP) and gross temperature lift (GTL) of the vertical SSHT were tested, respectively. The results show that bilateral falling film made it easier for the absorber to generate HTW and LPS directly. In case of producing water or steam, temperature at inlet and flowrate of heating water have similar effect on the useful output heat and COP. To some extent, we can improve the performance of SSHT by increasing the temperature.
The paper presents the gas permeability of marine sediments in the Shenhu Area of South China Sea. The sediments were obtained at the depth of 1600m below sea level. The solid density and volume weighted mean diameter of the sediments were 2.421 g/cm3 and 6.491 μm, respectively. The gas permeability of the marine sediments was measured by steady state method with confining pressures of 2MPa, 5MPa, 8MPa, 10MPa, 15MPa, 20MPa, 23MPa. The effective gas permeability of the sediments decreased from 2.638 × 10-16 m2 to 0.872 × 10-16 m2 as the confining pressure increased from 2 MPa to 23 MPa. The porosity of the sediments decreased from 41.82 % to 29.54 % as the confining pressure increased from 0 to 23 MPa. The gas permeability of the sediments was determined to be 1.535 × 10-16 m2 with confining pressure of 15 MPa and the porosity of 32.00 %. The longitudinal deformation of the sample was very sensitive to the confining pressure, and the compressibility of the sample in the radial direction was not obvious. The particle size term in the classical Kozeny-Carman equation was revised by a correction factor (N), and the experimental results fitted well with the curves when N value was 2.40. The reference group experiments indicated that the measurement results were reproducible.
Analysis of electricity consumption is important because it concerns the resilience of a country. Data mining techniques are needed that can handle fluctuations in these data, one of which uses SVR. The best parameter search for SVR is the most important for forming the model. In this paper, we will discuss in detail the combination of SARIMA-SVR and Firefly algorithms. The firefly algorithm is one of the metaheuristic techniques that provides accuracy which proven by the value of MAPE and RMSE.
Participation in demand response (DR) has been explored for many large energy using assets based on day-ahead markets. However, little is known about the use of multiple energy markets or DR for open canal systems. In this article, we propose the use of multiple flexible energy markets to enable DR for open canal systems in the Netherlands, where many large pumping stations are used for flood mitigation. We observed that the Dutch market is not yet rewarding DR, with relatively low-priced fixed-price contracts. However, when applied to the German market scenario, a cost saving of 13% was found. In conclusion, the method of combining two flexible energy markets seems successful. However, more simulations and research are needed to explore the full potential.