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Abstract The absorption refrigeration system driven by low grade heat sources, especially the waste heat sources, becomes more and more attractive in recent decades. However, most traditional absorption systems cannot achieve a high utilization rate of the waste heat with limited heat capacity. These systems are usually designed to obtain heat in the generator, which means that the waste heat sources cannot be utilized to the temperature lower than the generator temperature. This paper proposed a new structure heated by heat conduction oil in the generator and electric heating rings around the stripping section. This structure can simulate the temperature-distributed heat sources when the electric heating rings work. It can also simulate a traditional generator when the electric heating rings do not work. Influences of different heat distributions are analyzed in detail in this paper. The results show that the heat sources utilization rate will increase with the increase of the heat in the stripping section, while the coefficient of performance will be negatively affected by the increasing heat in the stripping section. By optimizing the heating structure, the coefficient of performance can be similar to that of a traditional system when the heat is just added in the middle and lower part of stripping section. The optimum utilization rate of heat sources in this test model can reach 1.8 times to that of a traditional system. Under this heating model, the lowest temperature required in the heating section is 82 °C when the heat conduction oil inlet temperature is 169 °C. It is much lower than the temperature inside the generator, which is 137.3 °C.

With increasing concern over global climate change and rapid rise in energy consumption on the data-driven market, data centres are an important renewable energy target. As cooling contributes a substantial portion of the energy use of data centres, minimising the cooling energy demand in data centres is one of the main objectives for improving renewable energy. This paper investigates overall energy consumption and the energy efficiency of the cooling system for a data centre in Finland as a case study. The temporal energy consumption characteristics, cooling infrastructure and operation of the data centre are analysed. The main problems associated with cooling energy efficiency and the factors that may contribute toward higher efficiency are identified and further suggestions are put forward. Results are presented of an extensive evaluation of the energy performance of the study data centre with a view to energy recovery. The conclusion we can draw is that even though the analysed data centre demonstrat...

Abstract For biomass/waste fueled power plants, stricter regulations require a further reduction of the negative impacts on the environment caused by the release of pollutants and withdrawal of fresh water externally. Flue gas quench (FGQ) is playing an important role in biomass or waste fueled combined heat and power (CHP) plants, as it can link the flue gas (FG) cleaning, energy recovery and wastewater treatment. Enhancing water evaporation can benefit the concentrating of pollutant in the quench water; however, when FG condenser (FGC) is not in use, it results in a large consumption of fresh water. In order to deeply understand the operation of FGQ, a mathematic model was developed and validated against the measurements. Based on simulation results key parameters affecting FGQ have been identified, such as the flow rate and temperature of recycling water and the moisture content of FG. A guideline about how to reduce the discharge of wastewater to the external and the withdrawal of external water can be proposed. The mathematic model was also implemented into an ASPEN Plus model about a CHP plant to assess the impacts of FGQ on CHP. Results show that when the FGC was running, increasing the flow rate and decreasing the temperature of recycling water can result in a lower total energy efficiency.

In this work, maize residue pellets were torrefied in a macro thermogravimetric analyzer with simulated dry flue gas from mixing of CO2 and N2. The effects of temperature (220–300 °C), residence time (10–40 min), and the presence of CO2 (0–18% v/v) in the reacting gas were investigated on products’ yields, distribution, and torrefied pellet properties such as higher heating value (HHV), elemental composition (C, H, O, N, S, K, and Cl), grindability, and moisture uptake ability. Temperature and residence time were found to affect the distribution of products’ yield and the properties of torrefied pellets considerably. In comparison with the untreated biomass pellets, the torrefied pellets appeared to have improved HHV and grindability but reduced moisture uptake ability. In the presence of CO2, the Boudouard reaction caused slight reductions in the C content and HHV of the torrefied pellets. Changes in torrefaction conditions did not prove to have a statistically significant effect on S, K, and Cl contents of the torrefied biomass materials.

Abstract Bitumen recovery by steam-solvent coinjection involves the coupled thermal/compositional mechanisms for reduction of bitumen viscosity. Reliable design of such processes requires reservoir flow simulation based on a proper phase-behavior model so that the oleic-phase viscosity near the steam-chamber edge can be modeled reliably. However, the effect of bitumen characterization (e.g., the number of pseudo components used) on steam-solvent coinjection simulation has not been studied in detail, and can be realized only after running multiple reservoir simulations, which is time consuming. There are two main objectives in this paper. One is to develop a reliable method for bitumen characterization by improving the fluid characterization method that was recently developed based on perturbation from n-alkanes (PnA). The other is to develop a novel analytical method for assessing the sensitivity of a particular coinjection simulation to bitumen characterization without having to perform reservoir simulations. A simulation case study is given to validate this analytical method. A proper number of pseudo components for bitumen characterization cannot be determined without considering the effect of phase behavior on the oleic-phase viscosity at chamber-edge conditions in steam-solvent coinjection simulation. Results show that the analytical method developed in this research can detect the sensitivity of recovery simulation to bitumen characterization without performing multiple flow simulations using different sets of fluid models. The PnA-based method developed for bitumen characterization gives reliable predictions of phase behavior for bitumen/solvent mixtures with a small amount of experimental data.

Abstract Four power generation options covering the spectrum of methods of fossil fuel power generation were used as the base cases to determine the resultant increase in base case levelized generating costs resulting from CO2 capture from the flue gas of a 500 MWc power station by liquid scrubbing technology. Suitable liquid scrubbing technology for CO2 capture was investigated only for end of pipe treatment, after upstream FGD (where applicable), for each of the options of a 500 MWe power station from coal and natural gas at a coastal site in the Netherlands. The three coal options were based on pulverised fuel, IGCC, and coal combustion in a mixture of oxygen and recycle gas respectively, whilst the natural gas option was based on a sulphur free NGCC. Only commercially proven liquid scrubbing technology screened in economic and technical terms. Inhibited MEA (monoethanolamine) was the most acceptable for the conventional pulverised coal fired power station, the IGCC coal fired power station and the NGCC plant. Selexol® was the most suitable for combustion of coal in the recycle mixture. In all cases pre treatment was necessary to remove traces of NOx and/or SO2 which otherwise would cause solvent degradation. As a consequence of CO2 capture, drastic reductions of both acid gases and particulates occur. The reduction in overall generating efficiency over the four options ranged from 2.4 to 13.5 per cent corresponding to an increase in power station nameplate capacity of 540 to 740 MWe to achieve a net export of 500 MWe after CO2 capture and regeneration. Investment costs increased substantially by between 52 to 108 per cent in terms of $/kWso. Over the range of options the resultant levalised base case generating costs increased from 22 to 108 per cent. The conventional PF coal power station showed an increase from 53.4 to 80.38 mills/kWhso and the natural gas (sulphur free) NGCC plant showed an increase from 32 to 50.24 mills/kWhso. In the case of the non conventional combustion of coal in recycle gas the cost increased from 83 to 101 mills/kWhso. Because the base case selected for the coal based IGCC plant required CO2 to be captured at almost atmospheric conditions, rather than at higher pressure, the costs were seriously distorted and are not readily comparable with the other options. The nett parasitic effect was not only to substantially increase investment costs but also to substantially increase the basic cost of electricity irrespective of the type of fuel and method of power generation. The balance between a CO2 tax and CO2 capture cannot be inferred without taking into cognisance the additional cost of CO2 disposal.

Abstract Given the need to reduce the CO2 emissions coming from the manufacturing sector, it is important, for planning purposes, to know which countries and which manufacturing sub-sectors have the greatest potential for reducing energy use. Using data from the International Atomic Energy Agency and the United Nations Industrial Development Organization, the authors estimate trends in global decoupling of energy use and manufacturing value added, compare energy-use intensity in six country groups and estimate the potential for reducing energy use and CO2 emissions under two scenarios and compare selected sub-sector energy intensity and estimate the potential for reducing energy use CO2 emissions. The comparison of energy intensities across country groups and among countries suggests that there still remains significant potential to reduce energy use and associated CO2 emissions. The analysis of four sub-sectors in developing and transition economies also shows similar but varied potential for reducing energy use and associated CO2 emissions.

Cylindrical graphite microbial fuel cell (MFC) configuration designed by eliminating distinct casing and membrane was evaluated for bioelectrogenesis and treatment of real-field wastewaters. Both petroleum refinery wastewater (PRW) and Labanah whey wastewater (LW) were used as substrates, and investigated for electricity generation and organic removal under batch mode operation. PRW showed higher bioelectricity generation (current and power generation of 3.35mA and 1.12mW at 100Ω) compared to LW (3.2mA and 1.02mW). On the contrary, higher substrate degradation efficiency was achieved using LW (72.76%) compared to PRW (45.06%). Superior function of MFC operation in terms of volumetric power density (PRW, 28.27W/m3; LW, 23.23W/m3) suggesting the feasibility of using these wastewaters for bioelectricity generation. Large sources of wastewater that generating in the Middle-East countries have potential to produce renewable energy from the treatment, which helps for the sustainable wastewater management and simultaneous renewable energy production.

Abstract Sugarcane is a major crop cultivated globally and the residue left over after the crop harvest and extraction of juice is a good biomass source that can be used for the production of several useful chemicals. The sugarcane bagasse is an excellent substrate for the production of various biochemicals and enzymes through fermentation. Now major interest is focused on the utilization of these residue for biofuel production. The sugarcane crop residue is rich in cellulose and hemicellulose, hence it can be used for the production of bioethanol and other liquid transportation fuels. The present review gives a detailed account of the availability of sugarcane residue and various commercially important products that can be produced from this residue. It also provides recent developments in R&D on the bioconversion of sugarcane crop residue for value added products.