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Abstract To alleviate the shortage of natural gas resource and ease carbon emissions, a novel solar-driven combined cooling, heating and power (CCHP) system is designed and optimized using the genetic algorithm in the work. Different from the process of direct combustion in a conventional CCHP system, natural gas is firstly converted into syngas by a solar-driven natural gas reforming step, which is consumed in an efficient tri-generation system. Energy, economic and environmental evaluations on five office buildings in different climate zones in China are implemented to validate the advantages of the proposed system. Results show that the annual maximum primary energy saving, total cost saving, and CO2 emission reduction are 69.76%, 49.80%, and 71.55%, respectively. The system located in severe cold zones, where solar energy is abundant and building requires more heat load in whole year, achieves the highest benefits in comparison with separate systems. Furthermore, the sensitivities on the price fluctuations of electricity, natural gas and solar field to the system profits are investigated, which indicates that the influence of electricity price on the system performance is the most significant. Thus, a promising method for reducing the natural gas consumption and improving the utilization efficiency of solar energy is provided.

Abstract Fouling is one of the most significant problems for internally enhanced tubes installed in the shell and tube condensers. Due to the lack of long-term test data, current fouling models are developed based on accelerated particulate fouling tests that have the low precision and hence are inapplicable for predicting combined fouling in most practical cooling tower systems. In addition, the constant values of fouling resistance (factor) recommended by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) are extremely limited under different operating conditions. To overcome these challenges, this research developed and validated two fouling prediction models based on experimental long-term tests. One of the models was in the form of a ratio of asymptotic fouling resistance of the enhanced tube to that of the plain tube ( R f ∗ / R f , p ∗ ), and the other one was in the form of the asymptotic fouling resistance of the directly enhanced tube ( R f ∗ ). Both models considered water quality, water velocity, and the tube geometries as the variables with the acceptable accuracy for prediction. 1) For the water quality, the parameter of valid concentration ( C com ) of cooling water was defined in this study, which reflected the potential amount of valid components to form the fouling. 2) For the water velocity, its impacts on the two critical parameters of the fouling process: sticking probability ( P ) and deposit bond strength ( ξ ) were investigated using experimental studies. Test results showed that in enhanced tubes with the increased water velocity the sticking probability ( P ) decreased continuously while the deposit bond strength (ξ) initially increased, and then, decreased. 3) For the tube geometries, by taking the parameters of tube geometries as variables the multi-variable correlations of the sticking probability ( P ) and deposit bond strength ( ξ ) were developed. From the results the generalized fouling prediction model as a ratio of asymptotic fouling resistance ( R f ∗ / R f , p ∗ ) was recommended for the application in HVAC&R industry due to its suitability and accuracy in practical project applications.

Abstract China has the advantage of learning from the mistakes made by nations that have developed their nuclear power energy system in the last century. Such mistakes encompass the lack of sustainable development of the nuclear energy and poor planning in the back-end of the nuclear fuel cycle. The present paper studies the evolution of a double strata cycle with fast reactor gradually replacing the LWR. It starts from 2035 and covers the historical development of nuclear energy in China to the year 2100. The paper studies the ADS impact on the NFC and estimates the number and the deploying schedule of the ADS reactors to limit the accumulation of minor actinides. The other aspects considered here are natural uranium resources, fuel utilization efficiency, proliferation and diversion risks, spent fuel production and overall materials flow. Additionally, perturbation calculations were performed to evaluate the impact of the uncertainty on key parameters. The results are discussed in view of the Chinese nuclear fuel cycle plan and their policy implications are thoroughly evaluated.

Waste printed circuit boards is one of the main electronic waste,which has serious pollution,it has valuable metal and nometal.So its processing method is a very complex problem.There are a variety of recovery methods since the birth of waste printed circuit boards,and the most widely used method is mechanical method,which is practical and avoids the problem of environmental pollution.This article describes the recovery process of mechanical method of recycling waste printed circuit boards and the equipment used, and summarizes the status quo of mechanical method of recycling waste printed circuit boards in China and abroad.

Abstract Standardization of biogas technology is immensely important for the promotion of the biogas industry worldwide. China has built a complete biogas standard system, which is divided into common, household biogas, biogas engineering, biogas digester for domestic sewage treatment, output utilization, and service system standards. The problems and potential barriers for biogas standardization in China are analyzed and come down to sluggish standard, overlapped standard, government-dominated standard, and lagging international standard. Accordingly, all potential biogas standards should be evaluated and placed under the same department. China Biogas Society and China Association of Rural Energy Industry play leading roles in developing enterprise or group/association biogas standards and ISO biogas standards. The bio-natural gas standard system and experimental standardization should be developed as well to replenish biogas standard system. A paradigm shift in biogas standardization should be from government-dominated to market-oriented model. The lessons learned for other developing countries includes expanding standardization to multi-aspects to realize full lifecycle control and management, building rapid responding mechanism of standardization to adopt industry transformation, integrating outdated standards into new versions, and establishing market-based standard system.

In this study, KOH and ZnCl2 were impregnated into sewage sludge as activation agents to produce activated sludge char in the pyrolysis step for the De-NOx process. The emission characteristics of volatile combustion from the pyrolysis of raw sewage sludge (SS-Raw), sewage sludge spiked with KOH (SS-KOH), and sewage sludge spiked with ZnCl2 (SS-ZnCl2) were investigated. In addition, the De-NOx effects and the characteristics of the prepared chars, including specific surface areas, pore distributions, functional groups, were explored. The exploration results showed that the pollutants generated during the volatile combustion process could be divided into primary pollutants (SO2, NO, N2O, and HCl) and minor pollutants (CO, NH3, and HCN). Under the conditions of oxygen-rich combustion, SO2 and NOx emissions from SS-KOH were 0% and 113.2% of those from SS-Raw respectively. SS-ZnCl2 exhibited the similar SO2 and NOx emissions to those of SS-KOH. However, SS-ZnCl2 released considerable HCl during the pyrolysis process, thus limiting its application. Sludge char from SS-KOH (SC-KOH) also exhibited the best De-NOx performance compared to the chars from SS-Raw and SS-ZnCl2 and the De-NOx efficiency was 56% higher than that of sludge char from SS-Raw (SC-Raw). Therefore, with KOH-impregnated SS, activated sludge char can be produced via one pyrolysis step and used in the De-NOx process.

This study evaluated the effectiveness of shrimp shell biochar (SBC) and nickel (Ni) loaded SBC in increasing methane yield during anaerobic digestion of food waste. The results indicated that the methane yields of control (without SBC), SBC, SBC loaded with the low concentration of Ni, and SBC loaded with the high concentration of Ni were 81.8, 116.1, 134.7, and 99.2 mL/(g·VS), respectively. SBC promoted the efficiency and stability of the whole anaerobic digestion process including hydrolysis, volatile fatty acid conversion and methanogenesis. While the invigorating effect of loaded Ni at the low concentration of 0.88 mg/g was mainly concentrated in methanogenesis, the inhibition effect of the high Ni concentration was comprehensive. SBC helped Methanosarcina proliferation, and low concentration Ni promoted the number and activity of Methanosarcina and Methanosaeta. The results show that biochar loaded with a low level of trace elements such as Ni can promote the anaerobic digestion process.

Abstract Sustainability is an important and difficult consideration for the stakeholders/decision-makers when planning a biofuel supply network. In this paper, a Mixed-Integer Non-linear Programming (MINLP) model was developed with the aim to help the stakeholders/decision-maker to select the most sustainable design. In the proposed model, the emergy sustainability index of the whole biodiesel supply networks in a life cycle perspective is employed as the measure of the sustainability, and multiple feedstocks, multiple transport modes, multiple regions for biodiesel production and multiple distribution centers can be considered. After describing the process and mathematic framework of the model, an illustrative case was studied and demonstrated that the proposed methodology is feasible for finding the most sustainable design and planning of biodiesel supply chains.

Abstract A novel waste incineration power system highly integrated with a supercritical CO2 power cycle and a coal-fired power plant has been developed. In the hybrid configuration, the supercritical CO2 cycle gains energy from the superheater of the waste-to-energy (WTE) boiler, and the saturated steam produced by the WTE boiler is employed to heat the feedwater of the coal power plant. Consequently, the cascade energy utilization of the waste can be realized with the improvement of the WTE process. The performance of the proposed integrated scheme was thermodynamically and economically evaluated as compared to the conventional separate scheme, based on a 500 t/d incineration unit and a 300 MW coal power plant. The results indicate that the waste-to-electricity efficiency is promoted by 8.34 percentage points with an additional net power output of 3.33 MW, when adopting the proposal. The total exergy efficiency and the exergy efficiency of waste-to-electricity are increased by 0.43 and 7.88 percentage points. Additionally, the proposed system performs excellently under various boiler loads. Due to the integration, the net present value of the WTE project rises by 18.17 M$ and the dynamic payback period is reduced by 4.20 years. Therefore, the new design is extremely feasible and profitable.