The energy performance of air source heat pump water heaters decays with increasing time due to improper operation and maintenance. In this paper, a quantitative study is conducted on the energy performance decay of air source heat pump water heaters and the potential improvement of long-term energy performance. First, the energy performance decay of five heating systems in Shanghai was studied on site. The results showed that the Annual Performance Factor of the air source heat pump water heaters
decayed by 5%-6% per year during the first six years of operation. Then, a Service Life Cycle Performance Factor model was proposed for further evaluation of the long_x0002_term energy performance. Case studies combined with simulations showed that the Service Life Cycle Performance Factor could be improved by 8.0% to 12.2%.
Cardiovascular disease and obesity are the number one causes of death. Consumption of unhealthy chicken fat and waste cooking oil in Indonesia is still very high with the aim of reducing household spending without reducing the quality of the taste of the food. This study produces biodiesel using a modified reactor which is applied in the home industry using feedstocks of mixture of chicken fat and waste cooking oil with various compositions, calculates the economic value of biodiesel products, and tested with biodiesel properties. The purpose of this research is to produce biodiesel from home industries that fulfill the biodiesel properties standards and calculate the economic value of the biodiesel produced so that it can increase the income per capita of the Indonesian people.
The research method is a development research of applied biodiesel production in the home industry from feedstocks mixture of chicken fat and waste cooking oil 1:3, 1:1, and 3:1 with a modified biodiesel reactor with a capacity of 5-8 liters. Biodiesel production by esterification-transesterification reaction. Biodiesel from home industry is calculated for its economic value and business opportunities, and then tested with fuel properties: flash point ASTM D 93, cloud point ASTM D 975, density ASTM D 1268, kinematic viscosity ASTM D 445, and alkyl ester content EN 12514.
This study includes a cost analysis of the proposed biodiesel production method to evaluate whether the method would be a feasible alternative for low income families to develop it as a home industry as a mean to ammend their income. The result of the analysis shows that the production cost of the proposed method is lower than the current selling price of the Government’s subsidized biodiesel price, making the method to be an attractive choice for a home industry alternative.
Metal-organic framework (MOF) is a promising adsorbent material to replace the conventional ones for many applications such as cooling and desalination. In this study, we report the effect of coating thicknesses using binder-agent aqueous solution-based synthesis strategy on the cyclic performance of aluminum and zirconium MOFs. The results showed that the coated MOFs enhances the cyclic performance over the neat granular and powdered forms. Moreover, the maximum effective coating thickness that provides faster cycle time compared to the neat adsorbent material is 0.85mm in aluminum MOF (aluminum fumarate), while it is 1.1mm in zirconium MOF (MOF-801). The enhancement of the coating thickness on the heat pump application is also studied.
The growing frequency of natural disasters, such as hurricanes and flooding, have brought new challenges including higher uncertainty of power supplies to the reliability of modern distribution networks. Resilience is introduced in the electrical engineering field to quantify the ability of a system to withstand and recover from external disturbances. This paper proposes a novel algorithm to optimize strategies for enhancing distribution network resilience by branch upgrade. According to the Extreme Value Theory, the method determines the failure probability of branches based on their physical strength under hurricanes during a designed lifetime. The method of Monte Carlo simulation is applied in the optimization model to maximize resilience. The result shows the optimal solution converges and compared with traditional methods that enhance main branches or upgrade as many branches as possible, the proposed method has a significant advantage in seeking the globally optimal solution.
Due to the natural calamities and pandemics, the
need for a decentralized freshwater system is the need
for a better future. Solar still is the only decentralized
thermal desalination system whose efficiency depends
on various parameters like solar insolation, thermal
insulation, water depth from the glass covers, etc.
Thermoelectric modules are employed to increase the
efficiency of solar still. The proposed study presents a
disruptive approach of using the thermoelectric module
to develop a new decentralized desalination system for a
freshwater generation. In the proposed research, the
thermoelectric module is used as a powerful heat pump
by ensuring a very low-temperature difference between
the hot surface and the cold surface of the
thermoelectric module. The latent heat released after
condensation is utilized in a closed-loop operation to
enhance the system’s efficiency. The efficiency of the
proposed method is 288% and 167% when operating the
thermoelectric module at the mid-current region and
maximum current region of the cooling curve of the
thermoelectric module. A MATLAB simulation is
conducted to evaluate the system by considering valid
assumptions, further a prototype of the system is
fabricated, experiments are in progress.
Nowadays, zero discharge of flue gas desulfurization (FGD) wastewater in coal-fired power plants has attracted great attention from all over the world. In this work, the effects of initial particle size of droplets (A), nozzle atomization cone angles (B) and initial velocity of droplets (C) on the evaporation characteristics of FGD wastewater in the spray drying tower of a 600 MW coal-fired power plant were studied numerically, and the interaction of influencing factors on evaporation characteristics of wastewater was investigated using response surface methodology (RSM). Moreover, the quadratic regression equation of coded factors with the maximum residence time of droplets (T) was given and the optimized values of each influencing factor were obtained. The results show that A, B, C, AC, A2 are significant model terms. The optimal operating parameters are considered to be: A = 60.109 μm, B = 90° and C = 150 m/s, with the corresponding T = 0.068 s. This study is expected to provide some reference for the engineering application of spray drying technology in the zero discharge of FGD wastewater of coal-fired power plants.
In order to reduce carbon dioxide emissions in the environment while improving the efficiency of biomass utilization, the use of coal-fired units coupled with biomass power generation is one of the important ways to achieve carbon reduction in coal-fired units in the future. In this paper, thermal calculations and analysis of a 300 MW power plant are studied based on the law of conservation of energy. The effects of coal-fired units on boiler parameters when blended with different types and proportions of biomass are investigated at BMCR, 75% THA, 50% THA and 30% THA loads, and corresponding improvement suggestions are given.
The hydrogen recirculation pump is the core component of the hydrogen supply system of the vehicle fuel cell engine. This paper innovatively put forward a conceptual design of a high-speed co-rotating array scroll hydrogen recirculation pump with the fixed radial sealing position to ensure easy sealing on radial clearance leakage and without the dynamic balance weight. The array scroll structure has advantages in reducing the radial size and could significantly improve the pumping efficiency and realize the compact and lightweight design.
The parametric design of the hydrogen recirculation pump was carried out. Then the aerodynamic performance of the hydrogen recirculation pump was analyzed via the three-dimensional unsteady numerical simulation with the advanced and effective dynamic mesh technology combining morphing and remeshing functions. Firstly, the transient flow field characteristics in the scroll hydrogen recirculation pump under the design operating condition were investigated. Secondly, the effects of rotating speed on performance parameters such as mass flow rate and isentropic efficiency of hydrogen recirculation pump were analyzed. Finally, the study focused on the effects of hydrogen humidity on the aerodynamic performance of the designed co-rotating scroll hydrogen recirculation pump.
The results show that the fluid in the compression chamber is low-speed, and the turbulence at the inlet of the suction chamber and the central exhaust chamber is intense. For the co-rotating hydrogen recirculation pump, the increase of speed will not only aggravate the gap leakage but also aggravate the over-compression phenomenon, resulting in the increase of exhaust loss as well as a decrease of isentropic efficiency at high speed. The highest isentropic efficiency occurs at the design speed, which is 84.31%. The humidity of hydrogen has a certain effect on aerodynamic performance. Compared with dry hydrogen, the isentropic efficiency decreases by 2.3% at 100% humidity, but the pressure and temperature rise change lightly, increasing by 0.63Kpa and decreasing by 0.3k respectively. Different hydrogen humidity has a great influence on the flow rate. With the increase of humidity, the gap flow velocity at the same rotating angle decreases by about 30m/s.
To study the migration law of chlorine in the hot flue gas environment of desulfurization wastewater. Based on the simulated experimental system of desulfurization wastewater evaporation, the composition and micro-morphology of gas-solid phase products during the evaporation of desulfurization wastewater are studied with the help of relevant analysis and testing instruments. The effects of different evaporation temperatures and pH values of desulfurization wastewater on the migration and transformation of chlorine in the process of desulfurization wastewater evaporation are also studied. The results show that gas-solid phase products are produced during the evaporation process of desulfurization wastewater, and the volatilization of chlorine increases with the increase of evaporation temperature, while the precipitation of chlorine decreases with the increase of pH value.
With the increasing energy consumption of electronic equipment, heat sink design becomes a significant problem to be solved. Topology optimization for conjugated heat transfer problems in heat sinks has attracted numerous attention recently for its high degree of freedom in design. In this paper, liquid-cooled heat sinks with five different inlet and outlet structure combinations are optimized using bi-objective topology optimization based on the density method. The channel layouts in heat sinks are optimized and multiple optimal structures and corresponding Pareto frontlines are obtained. The results show that the well-distributed fluid can enhance the thermal performance of the heat sink. Heat sinks with inlets and outlets having natural distribution functions have better performance. It is also found that larger solid thermal conductivity can cause fewer winding channels.