Abstract

The solid dust, ammonia sulfide, condensate, water and other liquid substances carried by natural gas in the pipeline transport process do serious harm to the safe operation of pipelines and instrumentation equipment along the way. The performance of the filter installed in the natural gas station and the user entrance is the key to the quality and flow of gas supply. The performance of the filter element changes dynamically with the use. If the filter element cannot be cleaned and replaced in time, the passing efficiency of gas will be seriously affected and the local resistance will soar and the passing flow will drop sharply, thus causing the safety problem of gas supply. In this paper, based on the investigation and analysis of the working condition of natural gas filter in actual engineering, a numerical model of natural gas filter was established, and the flow field inside the filter was simulated by means of CFD tool. The research shows that the change of inlet velocity has a great influence on the filtering effect. When the inlet velocity is about 13m/s, the filtering effect is the best, reaching more than 96%. Under limited conditions, it is recommended to give priority to the replacement of the lower filter element.

Abstract

The free piston engine generator (FPEG) is a novel energy conversion device which directly converts chemical energy of fossil fuels into electric energy by linear electric mover’s reciprocating linear motion driven by the combustion of combustible fuel-gas mixture. In this research, a validated numerical model was established to investigate the effect of the mover assembly mass on the system operation characteristics, engine performance, heat transfer loss and frictional loss. The results showed that the unique phenomenon of fast expansion and slow compression becomes more obvious as the mover assembly mass increases while the system operating frequency changes slightly. The indicated that the thermal efficiency decreases and the indicated specific fuel consumption increases as the mover assembly mass increases and the maximum indicated power is 3.37 kW when the mover assembly mass is 4.5 kg. The heat transfer loss increases and the friction loss changes slightly as the mover assembly mass increases when the input energy and the effective stroke keep constant. Lower mover assembly mass (lower than 4.0 kg) makes it difficult to achieve high operation compression ratio and higher mover assembly mass and high operation compression ratio would lead to excessive in-cylinder pressure and cause structural damage on the key components.

Abstract

Coupling perovskite solar cells (PSCs) and silicon solar cells (SSCs) in a V-shape tandem configuration is a promising strategy for efficient solar energy splitting utilization that requires no beam splitter mirror and only half usage amount of SSCs. Here we develop a method for the performance estimation of a V-shape tandem device, which employs a 23%-efficient practical heterojunction SSC as a sub-cell for demonstration. The investigation results of influences of PSCs’ bandgap, layer thicknesses and transparent electrode materials on the tandem performance provide a guidance in selecting and optimizing of PSCs for getting most energy output. The tungsten-doped indium oxide is proved to be the suitable material for PSCs in V-shape devices.

Abstract

The heat and moisture transfer efficiency is the key factor that affects the energy efficiency of an evaporative cooling system. The cooling of air in a wet channel is a complex process. It is necessary to find the dominant influences of this cooling process and increase the energy saving potential. This paper develops a validated computing model under the EES (Engineering Equation Solver) environment, and numerically explores the heat and moisture transfer process in channels of a dew point evaporative cooler. The results show that it always achieves the highest evaporation efficiency within 0.4m from the entrance of the wet channel. That is to say, the effective length of the exchanging channel could be significantly shortened in contrast to the popular products widely reported.

Abstract

In order to evaluate the energy efficiency of a dew point evaporative cooler from the views of “quantity” and “quality” of energy, based on the second law of thermodynamics, the influence of intake air temperature, air flow velocity and relative humidity on the distribution and variation of thermal exergy, chemical exergy, mechanical xergy, and exergy efficiency in the wet and dry channels of the cooler was studied by exergy analysis. The results show that the exergy efficiency of the cooler increases from 10.6% to 36.7% with the increase of the intake air temperature, and decreases from 21.8% to 9.5% with the increase of the relative humidity of the intake air and decreases from 18.2% to 9.1% with the increase of the air flow velocity. By studying the exergy efficiency under different conditions, it is known that the cooler still has a great energy saving potential. Combined with the exergy efficiency, the weak points of energy saving of the dew point evaporative cooler can be clearly known, thereby finding a method for reducing energy loss.

Abstract

Propose an experimental method for measuring evaporation characteristic parameters of COOLMAX
material. Measure the loss weight of the fabric after wetted and time parameters, calculate the evaporation rate of COOLMAX material. The experimental results show that there is no significant difference in evaporation rate and evaporation time between Jersey stitch surface and eyelet surface of COOLMAX fabric. The evaporation rate of fabric samples placed vertically is higher than that of fabric samples placed horizontally, which determine their application potential in evaporation cooling technology.

Abstract

Reducing the high heat flux central processing unit temperature under a lower pressure drop has become essential to data center cooling. Based on a chip with a heat flux density of 80 W/cm2, this study uses COMSOL Multiphysics simulation software to study the cooling effects of different structures of fin-type water-cooled radiators. This study analyzed the change in chip temperature, pressure loss in the radiator, and comprehensive heat transfer coefficient of the radiator under different flow rates by changing the area of the bottom plate, the position of the water inlet and outlet, and the gap length of the finless area. The results show that the heat dissipation effect is best when the heat sink area is close to the chip area. Additionally, it was determined that a moderate gap length has a certain optimization effect on the finned heat sink. Finally, the optimized structure for a finned, water-cooled radiator is proposed.

Abstract

Existing research has active contributions to the P2P trading framework development, such as cost minimisation for distributed power generation, local supply and demand balancing, prosumer engagement, pricing model development, and trading security, etc. These technical developments actively contribute to the P2P energy trading infrastructure development. In order to enhance the market penetration of the P2P energy trading concept, we need suitable business models for different energy markets across the globe based on the available technical infrastructures for the P2P energy trading. For this purpose, this study offers a novel overview of the P2P energy trading from the existing literature based on a business model canvas strategy. With the support of the business model canvas, we analyse the existing P2P energy trading literature in terms of nine business model development elements, namely customer segments, customer relationships, key partners, value proposition, channels, key resources, key activities, cost structure, and revenue streams. Our study contributes to the P2P energy business model development, which also reveals new research areas for the P2P energy trading.

Abstract

Biogas is one of the most crucial renewable energy and achieving high-efficient heat exchangers is the key to improve its production. In this study, the effect of pulsating flow on heat transfer in a twisted hexagonal tube with manure slurry was investigated for the first time by using computational fluid dynamics CFD. The performances of pulsating flows were simulated under different conditions, including the inlet velocity, frequency, and amplitude of pulsating flow in the twisted hexagonal tube with different torques. Pressure drops at different frequencies were further investigated. Moreover, the mechanism of heat-transfer enhancement was revealed with the evolution of the heat-transfer coefficient over time. It was found the pulsating flow achieves an 18.9% enhancement at low torque.

Abstract

Due to the high interconnection of the power system and natural gas system, recovery behaviors of the two systems would inevitably affect each other. It is essential to study a coordinated restoration strategy to enhance the resilience of the whole system in case of potential disruptions. In this paper, a novel restoration framework for interdependent gas and power systems (IGPSs) is proposed. Firstly, the restoration strategy optimization model with the objective of maximizing the resilience is constructed, in which the operating constraints of IGPSs are considered. Secondly, a reverse greedy method is proposed to efficiently solve the problem in a timely manner and the optimal restorative strategy can be obtained automatically. Finally, the effectiveness of the proposed method is validated by an IGPS test system.