Abstract

Thermophysical properties data presently available are insufficient to confidently design gas gathering and processing equipment at pressures near system critical points and cricondenbars. Poor understanding of supercritical fluid transport and physical properties at these pressures lead to over-design and higher operating and capital costs, where current uncertainties in fluid property predictions typically lead to equipment over designs of 15% or more. In this work, we present a wide range of experimental measurements made for different binary and ternary mixtures relevant to LNG processing. For this purpose, specialized state of art apparatuses were designed and validated over the temperature range (200 to 423) K at pressures above the mixture critical points, up to 35 MPa. The mixtures studied include (CH4 + C3H8), (CH4 + C3H8 + CO2) and (CH4 + C3H8 + C7H16); in the last of these the heptane contents was up to 15 mol %. Properties studied include density, viscosity, thermal conductivity, phase equilibrium, heat capacity, SLE and surface tension. The extensive experimental data gathered in this work were compared with a variety of different advanced engineering models frequently used for predicting thermophysical properties of mixtures relevant to LNG processing. In many cases the discrepancies between the predictions of different engineering models for these mixtures was large, and the high quality data allowed erroneous but often widely-used models to be identified. The data enabled the development of new and improved models, to be implemented in process simulation software, so that the fluid properties needed for equipment and process design can be predicted reliably which is essential for LNG industry. This in turn minimized environmental impacts and enabled reduced capital and operational expenditure by the LNG industry.

Abstract

As the bottleneck technology of electric vehicles (EVs), the battery has complex and hardly observable inside chemical reactions. Therefore, a precise mathematical model is crucial for the battery management system to ensure the secure and stable operation of the battery. Aiming at achieving a flexible, self-configuring, reliable Battery Management System (BMS), this paper mainly focuses on the following research points: Firstly, a Cyber-Physical system (CPS) based BMS is presented for a better use of battery data. Next, a data cleaning method based on machine learning algorithm is applied to the big data of batteries in electric vehicles. Finally, a rain-flow cycle counting algorithm-based battery degradation quantification method is proposed and a Stacked Denoising Autoencoders-Extreme Learning Machine (SDAE-ELM) algorithm-based battery modeling method is also built to deal with the influence of battery aging phenomenon. Using the battery data extracted from electric buses, model effectiveness and accuracy are validated. The error of the estimated battery terminal voltage estimator is within 2.5%.

Abstract

With the recent removal of the Feed in Tariff, and an imminent increase in VAT, the purchase and installation of solar PV on the domestic scale has become significantly less economic. Despite this change, no organization or individual has been able exhibit the magnitude of subsidy that will still be required to ensure a return on investment that encourages further uptake of rooftop PV, nor consider how this changes with the addition of further revenue streams (such as P2P trading or PPA-like agreements). Furthermore, concerns over methods for local voltage and thermal constraint management, and the environmental and economic costs of such methods, have developed as localized areas of very high PV penetration have been increasingly observed. In this paper, we determine the subsidy that should be provided to encourage an uptake rate of 0.5% homeowners/year under different revenue streams, determine the environmental and economic costs of local constraint management, and compare the results to avoidance of installation. The problems were solved using a combination of time series analysis, NPV calculations, power flow simulations, and optimization processes. It was found that none of the examined alternative revenue streams could currently provide the return on investment required (i.e. a FiT type subsidy is still required), that the required FiT would likely be insignificant on a national scale (provided P2P trading is employed), that simple reconductoring is the most economically and environmentally effective constraint management strategy, and that all constraint management strategies provide a large environmental benefit when compared to avoiding installation.

Abstract

Small-scale, distributed and low cost biomass power generation technologies are highly required in the modern society. There are big needs for these technologies in the disaster areas of developed countries and unelectrified rural areas of developing countries. This work aims to propose a technical feasibility analysis about the ultra-small power generation system based on the gasification of carbonized biomass wastes. A combined pretreatment processes including carbonization without external energy and densification were adopted to deal with various biomass. The 100 hours’ continuous operation results indicated that pelletization/briquetting of carbonized fuel realized the stable operation of an updraft gasifier if there were no blocking issues caused by the accumulation of tar. The cold gas efficiency and the carbon conversion during carbonized wood pellets gasification was about 49.2% and 70.5% with the equivalence ratio (ER) value around 0.32, and the power generation efficiency of the engine generator was 20.3% during the stable stage. Moreover, the maximum output power was 21 kW. Therefore, the comprehensive system covering biomass carbonization, densification, gasification, syngas purification, and engine system is feasible for ultra-small power generation. In conclusion, this small-scale biomass gasification and power generation system is a triad solution for independent energy production, and urban waste treatment, and CO2 reduction.

Abstract

Thermal energy recovered from Hot Dry Rock (HDR) or Engineered Geothermal Systems (EGS) is clean and renewable and may fulfill current energy demands. The long term flow characteristic of fractures is a key issue related to both the rate of geothermal production and the service life of the geothermal reservoir. We explore the long term fluid transport characteristics of a long (50 mm wide and 300 mm long) artificial fracture in granite at temperatures to 200 ℃. Permeability is measured under steady flow conditions in three stages: (1) stepped increments of temperature from 25 ℃ to 200 ℃; (2) constant temperature of 200 ℃ applied for 27 hours; (3) gradually decreased temperature from 200 ℃ to 25 ℃. The evolution of hydraulic aperture and permeability of the fracture is evaluated over these three regimes. Hydraulic aperture and permeability decrease with the increase in temperature. Uniform high temperatures result in a continued but gradual reduction in both hydraulic aperture and permeability. The reduction in hydraulic aperture and permeability of the fracture is permanent with marginal recovery as the temperature is reset to the original 25 ℃.Permeability increase during heating (stage 1), but decrease during high temperature production and then cooling (stages 2 and 3).

Abstract

A reasonable building energy efficiency benchmarking program plays an important role in energy consumption control and supervision. Previous studies have focused on the process of establishing a single benchmarking method, but few have compared the performance and outcomes of different methods. To fill this gap, this paper selects two benchmarking methods— multiple linear regression (MLR) based on Energy Star, and stochastic frontier analysis (SFA) to develop benchmarking models. We demonstrate each method using data on the energy and building characteristics of 45 four- and five-star hotel buildings located in Chongqing, China. To compare the consistency and explanatory ability of two methods, we first utilize the Spearman rank correlation analysis to test whether these methods have consistent energy efficiency ranks and then present Sankey diagrams to further reveal the interactions of the estimated energy efficiency scores obtained from these methods. The results show that even though the ranks of sampled buildings are basically consistent, the energy efficiency scores have significant differences especially for the buildings with low energy efficiency scores. Furthermore, we discuss the explanatory ability of each method. In addition to building characteristics, the design and operational characteristics of the HVAC system have great effects on building energy consumption.

Abstract

This paper studies a distinct perspective of a nano-grid to provide water needs at a survivable level for people with limited access to both electricity and drinkable water. It is shown that by considering the essential requirements of colonias, a portable treatment facility supported by a few photovoltaic (PV) panels and water storage tanks can provide the bare minimum living standards. This set up is defined as the survivable nanogrid. Given the primitive conditions, the proposed sizing and operation of the nanogrid leverages the flexibility of water filtration energy needs to compensate the fluctuating solar PV generation. The case study based on a water samples and historical weather data for targeted colonias in Texas suggests the unique benefits of joint optimization of both energy and water needs. It is shown that power generated by as little as 20 PV panels in each colonia can provide drinkable water for as many as 200 people in a sustainable and cost-effective manner. This finding is potentially generalizable towards for many other under-developed remote communities.

Abstract

This article approaches the consumption disaggregation methodologies for electricity bill breakdown, that aims to promote the user’s conscious consumption. That is, by accessing information about equipment use and consumption, consumers will become active agents in residential energy efficiency. The electric charges monitoring can be performed in several ways, however, regardless the used model, by analyzing the load curves of each equipment, through direct or disaggregated measurement (NILM), it is possible to understand the consumers and equipment behavior. This is, their electrical signatures, when compared to a standard, may indicate inefficient use or malfunction, by obsolescence or by default. Therefore, this paper concludes that the use of load disaggregation may go beyond its initial proposal to electricity bill breakdown, but to study behaviors of people and equipment in order to improve energy efficiency.

Abstract

This paper presents the Sustainable Campus project at UNICAMP – Brazil, started in January 2017. With a year in progress, the project introduces unexpected results and beyond the initial proposal. The organization structural change and the academic community support contribute to new advances in management, continuous improvement, multi professional participation and new public, private and social partnerships. Thus, the results shown here will serve as a guide for future projects and important points for sustainability development on university campus.

Abstract

With rapid urbanization and climate change, urban physical environment and energy demand are drawing greater attention. This paper conducts an empirical study on the new urban core zone of Jinan, China. Under the greater background of replacing old growth drivers with new ones, as the capital of Shandong Province, Jinan constructs a Prior Zone in this regard. This core zone occupies an area of 13km2 and will be built into a people-oriented green new town. In the urban design process, the author conducts a simulation analysis on urban physical environment and proposes optimization suggestions on urban design based on analysis results to eventually ensure construction of a new green and habitable urban area.