Efficiency enhancement of an industrial-scale thermoelectric generator system by periodically inputting thermal power

Chen, Leisheng,Lee, Jaeyoung Pergamon 2016 Energy Conversion and Management Vol. No.

<P><B>Abstract</B></P> <P>This paper discusses the practicality of transferring heat energy from exhaust waste gas produced by iron and steel factories to Dowtherm T, which is employed as a heat source of a thermoelectric generator (TEG) system. The electrical performance of an industrial-level TEG system when supplied with pulsed thermal power is optimized. Heated Dowtherm T is periodically pumped into an industrial-level TEG-based heat-to-electricity conversion system (i.e., TEG unit) to generate pulsed heat power. Twelve TEGs are used in the experiments; they are evenly separated and doubly sandwiched among three heat exchangers. The conversion efficiencies at duty cycles of 21% and 46% are measured and compared. The experiments show that pulsed thermal power yields better results than the steady-state power input in terms of the conversion efficiency under the same power input conditions; the thermal power of the lower duty cycle produces a greater enhancement of efficiency. Specifically, a maximum efficiency enhancement of 3.5× is achieved for a time period of 60min and duty cycle of 21%. These findings suggest that the thermal power input should be periodic rather than constant to greatly improve the electrical performance of an industrial TEG unit. The feasibility of employing periodic heating into waste heat recovery system is verified.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermoelectric generators (TEGs) have attractive features but low efficiency. </LI> <LI> Using pulsed power rather than continuous power improves the efficiency. </LI> <LI> This study is the first to use pulsed power in an industrial-scale TEG application. </LI> <LI> Heated Dowtherm T is periodically pumped to generate pulsed heat power. </LI> <LI> Pulsed power enhanced the efficiency by 3.5× under the experimental conditions. </LI> </UL> </P>

A 2.4 GHz-Band 100 W GaN-HEMT High-Efficiency Power Amplifier for Microwave Heating

Keigo Nakatani,Toshio Ishizaki 한국전자파학회JEES 2015 Journal of Electromagnetic Engineering and Science Vol.15 No.2

The magnetron, a vacuum tube, is currently the usual high-power microwave power source used for microwave heating. However, the oscillating frequency and output power are unstable and noisy due to the low quality of the high-voltage power supply and low Q of the oscillation circuit. A heating system with enhanced reliability and the capability for control of chemical reactions is desired, because microwave absorption efficiency differs greatly depending on the object being heated. Recent studies on microwave high-efficiency power amplifiers have used harmonic processing techniques, such as class-F and inverse class-F. The present study describes a high-efficiency 100 W GaN-HEMT amplifier that uses a harmonic processing technique that shapes the current and voltage waveforms to improve efficiency. The fabricated GaN power amplifier obtained an output power of 50.4 dBm, a drain efficiency of 72.9%, and a power added efficiency (PAE) of 64.0% at 2.45 GHz for continuous wave operation. A prototype microwave heating system was also developed using this GaN power amplifier. Microwaves totaling 400 W are fed from patch antennas mounted on the top and bottom of the microwave chamber. Preliminary heating experiments with this system have just been initiated.

셀룰러 네트워크에서 D2D 통신을 고려한 에너지 효율성 분석

정민채(Minchae Jung),최수용(Sooyong Choi) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.7C

본 논문은 셀룰러 네트워크에서 D2D (device-to-device) 통신을 고려한 시스템의 에너지 효율적인 모드 선택 기법 (mode selection) 및 파워 할당 기법 (power allocation)을 제안한다. 본 논문에서는 각 단말(device)의 에너지 효율성의 합 측면에서 에너지 효율성 (energy efficiency)을 분석한다. 먼저, 각 단말의 모든 가능한 모드에 대해 에너지 효율을 최대화하는 전송 파워를 계산한다. 제안하는 파워 할당 기법은 시스템 용량 측면에서 최적은 아니지만, 에너지 효율성 측면에서 최적의 성능을 보인다. 제안하는 전송 파워 할당 기법을 기반으로, 모든 가능한 모드에 대해 에너지 효율성을 구한다. 다음 단계로, 모든 가능한 모드 중에서 최대의 에너지 효율성을 갖는 모드를 구하며 동시에 해당 모드의 할당 전송 파워를 도출할 수 있다. 제안 기법은 에너지 효율성 측면에서 최적의 성능을 보이며, 기존 기법에 비해 월등한 성능을 보인다. This paper proposes an energy-efficient mode selection and power allocation scheme in device-to-device (D2D) communication system as an underlay coexistence with cellular networks. We analyze the energy efficiency which is defined as the summation of the energy efficiencies for all devices. The proposed scheme consists of two steps. First, we calculate the transmission power maximizing the energy efficiency for all possible modes of each device. Although the proposed power cannot maximize the system capacity, we prove that the proposed transmission power is the optimal power which maximizes the energy efficiency. In the second step, we select a mode which has the maximal energy efficiency among all possible mode combinations of the devices. Then we can jointly obtain the transmission power and the mode which can maximize the energy efficiency. The proposed scheme has the optimal performance with respect to the energy efficiency and outperforms the conventional schemes.

자주식 양파정식기 슬라이딩 메쉬형 기어박스의 동력전달 해석

이슬람나피울 ( Md Nafiul Islam ),알리모하마드 ( Mohammod Ali ),키라가샤피크 ( Shafik Kiraga ),초두리밀론 ( Milon Chowdhury ),권행주 ( Haing-ju Kwon ),정선옥 ( Sun-ok Chung ) 한국농업기계학회 2021 한국농업기계학회 학술발표논문집 Vol.26 No.1

An appropriate gearbox selection is essential to avoid transmission losses and convey the engine power to the transplanter components efficiently. Therefore, the objective of this research was to simulate the power transmission of a self-propelled onion transplanter gearbox for calculating the power loss and efficiency. The automatic transplanter power transmission scheme consists of wheels, and dibbling mechanism, and picking mechanism. A computer-aided gear efficiency calculation software package was used to develop a three-dimensional simulation model for the automatic onion transplanter. A V-belt with pulley and nine gear stages sliding mesh type gearbox were used to transmit power from engine to wheel and other transplanter components. The last two gear sets were used as dibbling and picking mechanism gear shafts, respectively. The transmission load was measured at the input shaft of the gearbox, and the driving axle load was measured at the final drive shaft. The load measurements were made at three-speed levels. The input power of the gearbox was 1.7 kW, and the last stage of power (picking scheme) was found as 0.8 kW. The overall efficiency of this gearbox was found as 83.39%. The outcomes of the research would provide a significant reference for the development a power transmission scheme for efficient automatic onion transplanting.

OFDM 통신 시스템에서 비선형 증폭기 특성을 고려한 전력 효율과 대역 효율

이재은,유흥균 충북대학교 컴퓨터정보통신 연구소 2003 컴퓨터정보통신연구 Vol.11 No.2

OFDM 시스템뿐만 아니라 모든 통신 시스템에서는 HPA(high power amplifier)의 비선형 특성을 고려하는 것이 중요하다. 본 논문에서는 OFDM 통신 시스템에서 전력 효율과 대역효율을 동시에 고려한 새로운 성능 평가지수(D)를 분석한다. IBO(input backoff)의 크기와 부반송파 수에 따라 다른 값을 갖는 비선형 왜곡 잡음 성분(N_(d))을 고려하며, 대역폭의 변화에 따른 대역 효율을 사용하여 성능 지수를 구함으로써 IBO에 대해 서로 상반관계(tradeoff)에 있는 전력 효율과 대역 효율의 특성을 분석하였다. It is very important to consider the nonlinear effects of the HPA(high power amplifier) not only in the OFDM communication systems but in the other digital communication systems. In this paper, we investigate a new performance figure-of-merit (D) that reflects the power efficiency and spectrum efficiency at the same time. The performance figure-of-merit is expressed to include both the spectrum efficiency and the power efficiency. E_(b)/(N_(o)+N_(d)) including the nonlinear distortion value (N_(d)) and the spectral efficiency depend on the magnitude of IBO(input backoff) and the number of subcarriers. Therefore, we analyze the variation characteristics of the power efficiency and spectrum efficiency which has the tradeoff relationship.

Efficient Wi-Fi Power Amplifier LTCC Module Using a Buck Converter With a Power Inductor Implemented in Ferrite-Filled PCB Technology

Sang-Woong Yoon,Trung-Sinh Dang,Ngoc-Duy-Hien Lai,Park, Jae Y. IEEE 2015 IEEE transactions on components, packaging, and ma Vol.5 No.7

<P>This paper presents a power amplifier module (PAM) that operates efficiently in low-power mode for IEEE 802.11g Wi-Fi applications. The PAM consists of a power amplifier (PA), a buck converter, and a power detector. Two packaging technologies were used to integrate the compact module: a low-temperature co-fired ceramic (LTCC) technology and a ferrite-filled printed circuit board (PCB) technology. The LTCC portion includes radio-frequency inductors, capacitors, transmission lines, and interconnection lines to minimize the overall size, while a power inductor for the buck converter is implemented in ferrite-filled PCB. The PA and the buck converter are designed in 2-μm InGaP/GaAs heterojunction bipolar transistor technology and 0.35-μm CMOS technology, respectively. The output power level is converted into a voltage by the power detector, and the voltage controls the buck converter, thereby optimizing the supply voltage of the PA. This adaptive supply voltage helps to improve the power-added efficiency (PAE) in the low-power regime while maintaining linearity. The PAM showed an error vector magnitude of less than 4% up to an output power of 22 dBm. The PAE is 8% and 11% at output powers of 11 and 16 dBm, respectively, representing respective improvements of 60% and 43%. The overall size of the PAM is 5×7.5×1.2 mm<SUP>3</SUP>.</P>

고효율 전력 증폭기를 위한 재구성성이 있는 전력 분배기

김승훈(Seunghoon Kim),정인영(In-Young Chung),정진호(Jinho Jeong) 한국전자파학회 2009 한국전자파학회논문지 Vol.20 No.2

본 논문에서는 저출력에서의 효율을 높이기 위한 전력 증폭기 시스템과 이 시스템에 필요한 재구성성이 있는 전력 분배기를 제안한다. 저출력에서의 효율을 높이게 되면, 무선 통신용 선형 전력 증폭기의 평균 효율을 높일 수 있다. 제안한 전력 분배기는 출력의 크기에 따라 고출력 모드와 저출력 모드로 동작한다. 각 모드에서 신호의 경로가 재구성되고 임피던스 정합도 이루어진다. 이러한 재구성성이 있는 전력 분배기는 두 개의 λ/4 결합 선로(coupled line)와 두 개의 스위치로 구성된다. 제작된 전력 분배기는 중심주파수 0.9 ㎓에서 고출력 모드일 때 반사손실(S11)과 삽입손실(S21)이 각각 -16.49 ㏈와 -0.83 ㏈, 저출력 모드일 때 반사 손실(S11)과 삽입손실(S31)이 각각 -16.28 ㏈와 -0.73 ㏈였다. 이 결과를 통해 각 모드에서 신호의 경로가 재구성되며 임피던스 정합이 이루어지는 것을 확인하였다. In this paper, high efficiency amplifier configuration is proposed using the reconfigurable power divider. In order to enhance average efficiency of linear power amplifiers for wireless communication, it is required to increase efficiency in low output power region. The proposed power divider operates in two modes, high power mode and low power mode, according to output power. In each mode, it allows impedance matches and low loss, which is made possible by employing two λ/4 coupled lines and two switches. The fabricated power divider shows the return loss (S11) and insertion loss (S21) of ?16.49 dB and ?0.83 ㏈, respectively, in low power mode. In high power mode, the measured return loss (S11) and insertion loss (S31) are ?16.28 dB and ?0.73 ㏈, respectively. This result successfully demonstrates the reconfigurability of the proposed power divider.

Resource Use Efficiency of Electricity Sector in the Maldives

SHUMAIS, Mohamed Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.1

The study measures the resource use efficiency of diesel based power generation in the Maldives and analyses factors which influence efficiency levels. Stochastic frontier analysis (SFA) technique is applied to data on 30 plants over two year period from 2016 to 2017. The study finds that technical efficiency scores varies from 0.44 to 0.98 across power plants. About 33 percent of the plants have scores below the mean technical efficiency score of 0.87. Empirical results indicate ownership and use of solar photovoltaic (PV) have an influence on improving efficiency levels. Privately owned power plants in resort islands obtained higher technical efficiency scores compared to public and community owned power plants. This is a significant finding as the first study that used power plants in tourist sector in a comparative study. Size of the power plants was not found significant, but relatively small installed capacities can also be efficient. This finding is important because in many inhabited islands installed capacities remain oversized compared to the load. The benchmarking exercise offers model power plants that are relatively efficient, for other power plants and policy makers in small islands to learn from.

DYNAMIC MODELING OF THE ELECTRO-MECHANICAL CONFIGURATION OF THE TOYOTA HYBRID SYSTEM SERIES/PARALLEL POWER TRAIN

C. MANSOUR,D. CLODIC 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.1

The hybridization of the conventional thermal vehicles nowadays constitutes a paramount importance for car manufacturers, facing the challenge of minimizing the consumption of the road transport. Although hybrid power train technologies did not converge towards a single solution, series/parallel power trains with power-split electromechanical transmissions prove to be the most promising hybrid technology. In fact, these power trains show maximum power train overall efficiency and maximum fuel reduction in almost all driving conditions compared to the conventional and other hybrid power trains. This paper addresses the model and design of the electro-mechanical configuration of one of the most effective HEV power trains: case study of the 2nd generation Prius. It presents the simulation work of the overall operation of the Toyota Hybrid System (THS-II) of the Prius, and explores not only its power-split eCVT innovative transmission system but also its overall supervision controller for energy management. The kinematic and dynamic behaviors of the THS-II power train are explained based on the power-split aspect of its transmission through a planetary gear train. Then, the possible regular driving functionalities that result from its eCVT operation and the energy flow within its power train are outlined. A feedforward dynamic model of the studied power train is next proposed, supervised by a rule-based engineering intuition controller. The energy consumption of the THS-II proposed model has been validated by comparing simulation results to published results on European, American and Japanese regulatory driving cycles.

2.45 GHz ISM대역 고효율 스위칭모드 E급 전력증폭기 및 송신부 설계

고석현,구경헌 한국항행학회 2020 韓國航行學會論文誌 Vol.24 No.2

A power amplifier of 2.4 GHz ISM band is designed to implement a transmitter system. High efficiency amplifiers can be implemented as class E or class F amplifiers. This study has designed a 20 W high efficiency class E amplifier that has simple circuit structure in order to utilize for the ISM band application. The impedance matching circuit was designed by class E design theory and circuit simulation. The designed amplifier has the output power of 44.2 dBm and the power added efficiency of 69% at 2.45 GHz. In order to apply 30 dBm input power to the designed power amplifier, voltage controlled oscillator (VCO) and driving amplifier have been fabricated for the input feeding circuit. The measurement of the power amplifier shows 43.2 dBm output and 65% power added efficiency. This study can be applied to the design of power amplifiers for various wireless communication systems such as wireless power transfer, radio jamming device and high power transmitter. 2.4 GHz ISM대역 전력증폭기를 설계하고 송신 시스템을 구현하였다. 고효율 증폭기는 E급이나 F급 증폭기로 구현 가능하다. 본 연구에서는 회로 구조가 간단한 E급으로 20 W 급 고효율 증폭기를 설계하여 ISM 대역 응용에 적용하도록 하였다. E급 회로 설계이론 및 회로 시뮬레이션을 통해 임피던스 정합회로를 설계하였으며 2.45 GHz에서 출력전력 44.2 dBm 및 전력부가효율 69%를 얻었다. 설계된 전력증폭기에 30 dBm의 입력전력을 인가하기 위하여 앞단에 전압제어발진기와 구동증폭기를 제작하여 입력전력 공급회로를 구현하였고, 제작한 전력증폭기는 43.2 dBm 출력 및 65%의 전력부가효율 특성을 나타내었다. 본 연구결과는 무선전력전송, 전파차단장치, 고출력 송신장치 등 다양한 무선통신시스템용 출력 전력증폭기 설계에 활용될 수 있다.