Advanced Materials Research Vols. 860-863

Abstract: The paper presents a numerical simulation to investigate the heat transfer enhancement of a rectangular pipe with longitudinal fins for the automobile thermoelectric generator. The fins were inserted near the pipe wall. The effects of flow rate (w_i=10m/s-50m/s), fin length ( l=100, 133, 200, 400), fin spacing (d=20, 30, 40, 50), fin height (h=20, 30, 40, 50) on Nusselt number (Nu), friction factor (f) and overall enhancement ratios (ƞ) are investigated under constant wall temperature , using air as woking fluid. Number calculations were performed with FLUENT code. The obtained results reveal that all geometric parameters have important effect on the thermal performance of pipe, and the finned pipe show better thermal performance than smooth pipe. It is also found that the overall enhancement ratios increase with increasing fin length and fin height, also the overall enhancement ratios decrease with increasing fin spacing. All finned pipes have good heat performance with ƞ greater than 1. The best overall enhancement of 1.25 was achieved for w_i=10m/s for which the fin dimensions is l = 400mm, d = 20mm, h = 50mm.

Abstract: Many power plants adopt air-cooled condensers (ACC) with finned tubes, using ambient air to condense turbine exhaust steam. Each condenser unit is mainly composed of two heat transfer surfaces like A and large diameter axial flow fans driving air. In the study of environmental wind effects, etc, due to the condenser unit size is bigger, it is necessary to simplify the condenser unit internal flow and heat transfer calculation, but the deviations introduced by these simplifies failed to get enough attention. In view of one condenser unit, three kinds of flow and heat tansfer combinated model were respectively investigated. A computational fluid dynamics software (CFD) is used to solve the problem.Research priority is analyzing the deviations of internal flow and heat transfer features in the condenser unit according to the extracted datum. The study gives some useful informatin to the design of a thermal power plant with an ACC system.

Abstract: With the rapid development of Chinese economy, making the energy consumption of HVAC increase sharply, HVAC energy saving has been an increasingly urgent event. This paper points out that the development of green energy is the need of energy saving and environmental protection, this paper introduces the application of green energy in the HVAC, how to develop new technology in HVAC and puts forward some opinions.

Abstract: In order to solve the problem that special users energy saving potential is unable to diagnose automotive online, a new automatic diagnosis of energy saving potential method based on online DSP was proposed. This proposed method, together with a variety of techniques like modern power electronics, digital signal processing, high precision and fast sampling, high capacity storage, human-machine interaction technologies and so on, was applied to develop a corresponding special users energy saving potential diagnosis detector. The hardware design and DSP energy saving analysis software design of the detector were described firstly, and the results of field test were presented to demonstrate its feasibility. It is shown that, its advantages include easy-to-use, low cost, highly reliable, strong intelligence and easy to promote, thus can effectively improve the efficiency of electrical energy audit and the degree of information and automation.

Abstract: The optimization of condenser vacuum is significant to improve efficiency and save energy in the power plant. Taking a 600MW unit as the research object, the condenser vacuum optimization model was established synthetically based on neural network, simulated annealing and biogeography optimization hybrid algorithm (SA-BBO). Circulating pumps power, slight increase of turbine power as well as the market value difference between coal and electric were included in the model. The objective function of the model is to maximize the profit of the power plant. The most effective combinations of the condenser vacuum and the circulating water pump were calculated eventually in different operating conditions by using characteristic analysis of variable condenser conditions. In a certain condition, running three circulating pumps for two steam turbines instead of two pumps can make the condenser vacuum reduce 0.49kPa, and increase revenue 110.2 yuan/h.

Abstract: To study the influence factors of energy efficiency operation index (EEOI), an EEOI model is established by taking a 46000-ton oil tanker as an example and with the aid of software. The factors affecting EEOI are divided into determined factors and random factors according to the Monte Carlo method. The time-change curves of EEOI are obtained and further analysis of the influence of the characteristics wave height and load on EEOI is made. Results show that improving the loading rate can effectively improve the EEOI and reducing the speed can make the EEOI drop, the higher the wave is , and the less the effects are. The method has a certain reference value for making energy efficiency management scheme.

Abstract: Blast furnace in steel industry consumes about 9% of annual energy consumption of domestic industry. Blast dehumidification is an important way to increase production and decrease coke ratio of blast furnace. The energy-saving blast dehumidification system uses heat pipe for air pre-cooling and re-heating before and after dehumidification. Because temperature of air has been decreased to a certain extent by pre-cooling, dehumidification energy consumption could be decreased. After dehumidification, temperature of the air could be increased by re-heating, thus the threshold temperature of the air sent into hot blast stove could also be increased, it would save energy and increase production of blast furnace. But this system has an extra heat pipe heat exchanger compared with traditional one, so the construction cost and pressure drop may be higher.

Abstract: The in-depth energy conservation of thermal power units is confronting new challenges under the varying operation conditions and ambient constraints. Compared with traditional optimal values, the description of energy-consumption benchmark state was proposed to describe the economic performance of thermal power units with the varying operation boundary, operation conditions and equipment performance. The energy consumption interactions of units were divided into 4 parts: parameters, equipment, subsystems and units. The models for energy-consumption benchmark states were established with the fuel specific consumption (FSC) setting as the optimization objective. Such a method was performed on a 600MW supercritical power unit and the results show that the energy-consumption benchmark state, which is related with the varying boundary, can reflect the boundary condition, operation lever and equipment performance. It makes significant reference for the energy-saving diagnosis and operation optimization of thermal power units under overall working conditions.

Abstract: In this paper the numerical simulation is performed by using the CFD soft FLUENT. A 3D geometric model is established and whose mesh is generated. The fields of the temperature, pressure and velocity in the computational domain are simulated. And the effect of the corrugation depth on the heat transfer and flow is analyzed.

Abstract: This paper analyzes the design of constant pressure water supply frequency control system based on SANCO - vm05 inverter with the built-in PID regulator and SWS water supply control. It’s replacing traditional way of water supply to eliminate the secondary pollution of water quality, improve the quality of the water supply, save energy by 20% - 40%, thus it’s proved as small investment and large gains.