Total Input Power Research Articles

Investigations on the Cycle Performance of a Diffusion Absorption Heat Transformer Using HCOOK as an Alternative to LiBr

Abstract A diffusion absorption heat transformer (AHT) is very potential to improve energy utilization efficiency and reduce carbon emission, because it can be totally driven by waste heat without electricity consumption. On the base of a simulation model, the cycle performance of a diffusion absorption heat transformer using HCOOK-H2O-R134a-TEGDME and LiBr-H2O-R134a-TEGDME is compared under specified temperatures of Generator A, Generator B, evaporator, condenser, low-temperature (LT) absorber, and high-temperature (HT) absorber. The influences of six temperatures on cycle performance are assessed and coefficient of performance (COP) is found more sensitive to the temperatures of Generator B and high-temperature absorber. High COP corresponds to small diffusion gas supply ratio and small proportion of the heat input to Generator A in the total thermal power input. The employment of HCOOK instead of LiBr is beneficial to increasing COP in optimized conditions. In the design temperature conditions, COP can be increased from 0.170 to 0.178 in the system using HCOOK instead of LiBr. Meanwhile, diffusion gas supply ratio, proportion of the heat input to Generator A, and pumping ratio (PR) of Lifting Tube B can be decreased to 0.368, 0.022, and 0.098, respectively. The diffusion absorption heat transformer will provide a new way to lift the temperature of low-grade heat for more availability without electricity input and improve the energy utilization efficiency.

Mechanical Booster Pump-Assisted Thermochemical Mode for Low-Grade Heat Storage and Upgrading: A Thermodynamic Study

To assure stable and dependable functioning of the thermochemical energy storage (TCES) system under unstable low-grade heat temperatures, three mechanical booster pump-assisted TCES (MBP-assisted TCES) modes operating with SrBr2·H2O/H2O, LiOH/H2O, and CaCl2·H2O/H2O are proposed for the application of heat storage and upgrading. The operating modes are the MBP-assisted charging mode (A mode), MBP-assisted discharging mode (B mode), and MBP-assisted charging and discharging mode (C mode). A thermodynamic model is established to evaluate the influences of condensing temperature, compression ratio, MBP isentropic efficiency, and reaction advancement on the heat source temperature and system performance from both energy and exergy perspectives. The results indicate that compared with the other two modes, the B mode is more effective in reducing the heat source temperature and achieving better system performance. Compared to the conventional TCES mode, the proposed modes can operate at lower heat source temperatures that can be minimized by up to 21∼25°C by employing the B mode with a compression ratio of 3.0 at the condensing temperature of 24°C. The B mode with SrBr2·H2O/H2O exhibits the highest energy and exergy efficiencies that the coefficients of performance based on total energy input and electric power consumed (COPtotal and COPelec), and exergy efficiency varies in the range of 0.53∼0.59, 7.4∼19.6, and 0.78∼0.95, respectively. In contrast, CaCl2·H2O/H2O shows the lowest system performance, but a higher heat output temperature can be required. In addition, to maintain the MBP discharge temperature below 180°C, there is a maximum permitted compression ratio that varies depending on the operating modes, operating conditions, and working pairs. The findings of this research can be used as theoretical references and suggestions for selecting MBP-assisted TCES modes, operating conditions, and working pairs for low-grade heat storage and upgrading.

Train-induced floor vibration and structure-borne noise predictions in a low-rise over-track building

Frequent train operations in metro depots can have adverse effects on the buildings’ occupants in terms of feelable vibration and noise. A method is proposed to predict vibration transmissions from columns into girders and subsequently into the floors. This method is quite efficient in modeling and computation, saving engineers time and computational cost. It is highly useful in the design phase for identifying undesirable feelable vibration and audible noise within buildings and for developing mitigation measures that improve human comfort, operation of sensitive equipment, and manufacturing.Train-induced ground-borne vibration in metro depots transmits into the upper floors of over-track buildings primarily through axial waves in the supporting columns. The vertical vibration of a column at a floor inputs mechanical power into the attached girders based on their impedance at the column. An analytical model of the girder impedance is developed that accounts for the coupling to the floor and for composite action where in-plane deformation in the floor stiffens the girder. Along with the measured vibration velocity levels at the columns, impedances of the coupled floor and girders are used to predict the mechanical power input at individual columns into the girders. The input mechanical power generates bending waves in the girders with subsequent transmission out into the attached floor along their length. The resulting average floor vibration levels in the bay are predicted in response to the total mechanical power input, which in turn radiate noise from the floor structure into the room.The overall model from vibration inputs at the columns to room noise levels was applied to a 4-story over-track building during train passbys under the building in the Qianhai Metro Depot in Shenzhen, China. The predicted average floor vibration levels and room noise levels were in good agreement with their corresponding measurements.

Dynamic characteristics modelling and analysis for dry screw vacuum pumps

This paper modeled the dynamic characteristics of dry screw vacuum pumps considering the forces induced by gas, gear, bearings, and rotor gravity, and discussed the load on bearings and gear comprehensively employing the proposed model. First, the balance equations on force and torque were proposed based on a simplified force analysis model for a test dry screw vacuum pump. Next, the detailed calculation methods of gas force, gear load, bearing load, and motor power were presented, respectively. Furthermore, the calculated motor power was verified by comparing the measured results from a test experiment. Finally, the gas force, gear load, bearing load, and bearing power loss under different inlet pressures was discussed comprehensively. Results showed that the proposed model could effectively analyze the load and power distribution for dry screw vacuum pumps. The torque of synchronous gear could be reduced by reasonably selecting the driving shaft. The axial gas force acting on the end face of rotors showed the main contribution for the power loss of bearings, which accounted for up to 3.2% of total input power. The obtained conclusions could guide the reasonable design and selection of the supporting and driving components for dry screw vacuum pumps.

InP photonic integrated multi-layer neural networks: Architecture and performance analysis

We demonstrate the use of a wavelength converter, based on cross-gain modulation in a semiconductor optical amplifier (SOA), as a nonlinear function co-integrated within an all-optical neuron realized with SOA and wavelength-division multiplexing technology. We investigate the impact of fully monolithically integrated linear and nonlinear functions on the all-optical neuron output with respect to the number of synapses/neuron and data rate. Results suggest that the number of inputs can scale up to 64 while guaranteeing a large input power dynamic range of 36 dB with neglectable error introduction. We also investigate the performance of its nonlinear transfer function by tuning the total input power and data rate: The monolithically integrated neuron performs about 10% better in accuracy than the corresponding hybrid device for the same data rate. These all-optical neurons are then used to simulate a 64:64:10 two-layer photonic deep neural network for handwritten digit classification, which shows an 89.5% best-case accuracy at 10 GS/s. Moreover, we analyze the energy consumption for synaptic operation, considering the full end-to-end system, which includes the transceivers, the optical neural network, and the electrical control part. This investigation shows that when the number of synapses/neuron is >18, the energy per operation is <20 pJ (6 times higher than when considering only the optical engine). The computation speed of this two-layer all-optical neural network system is 47 TMAC/s, 2.5 times faster than state-of-the-art graphics processing units, while the energy efficiency is 12 pJ/MAC, 2 times better. This result underlines the importance of scaling photonic integrated neural networks on chip.

Plasma-wall self-organization in magnetic fusion

This paper introduces the concept of plasma-wall self-organization (PWSO) in magnetic fusion. The basic idea is the existence of a time delay in the feedback loop relating radiation and impurity production on divertor plates. Both a zero and a one-dimensional description of PWSO are provided. They lead to an iterative equation whose equilibrium fixed point is unstable above some threshold. This threshold corresponds to a radiative density limit, which can be reached for a ratio of total radiated power to total input power as low as 1/2. When detachment develops and physical sputtering dominates, this limit is progressively pushed to very high values if the radiation of non-plate impurities stays low. Therefore, PWSO comes with two basins for this organization: the usual one with a density limit, and a new one with density freedom, in particular for machines using high-Z materials. Two basins of attraction of PWSO are shown to exist for the tokamak during start-up, with a high density one leading to this freedom. This basin might be reached by a proper tailoring of ECRH assisted ohmic start-up in present middle-size tokamaks, mimicking present stellarator start-up. In view of the impressive tokamak DEMO wall load challenge, it is worth considering and checking this possibility, which comes with that of more margins for ITER and of smaller reactors.

Influence of inlet gas volume fraction on energy conversion characteristics of multistage electric submersible pump

A local-regional power loss analysis method based on multiphase computational fluid dynamics (CFD) simulation results is proposed in this study. This method is used to investigate the energy conversion characteristics of a three-stage electric submersible pump under high inlet gas volume fraction (IGVF) conditions. Results show that the input power and effective power increase first and then decrease along the streamline. When IGVF increases from 0% to 14.5%, the total input power and total effective power decrease by 32.4% and 56.2%, respectively. In particular, the input power and effective power in R4 drop by 62% and 67%, respectively. The high gas volume fraction (GVF) area on the blade pressure surface near the impeller inlet causes the power decrease in R4. However, the input power in R6 increases by 47.5%. This condition is due to a jet flow near the impeller outlet causes the vortex and high GVF area in R6, thereby leading to a high liquid velocity area along the radial direction near the pressure surface of the impeller blade. The kinetic energy of the fluid in the jet region increases rapidly in accordance with Bernoulli equation and is converted into pressure energy in the vortex area. The total power loss increases quickly with IGVF. The power loss near the impeller outlet area at 14.5% IGVF is ten times higher than that of 0% IGVF condition and five times higher than that of 5% IGVF condition. This condition is caused by the large air pockets accompanied by vortices in the area. This work provides a theoretical basis for the design and optimization of the multiphase pump.

Forward Osmosis Absorption Heat Pumps for Space Conditioning and Graywater Purification: Cycle Development and Working Fluids Selection

Abstract A thermodynamic model is developed for a forward osmosis (FO) absorption heat pump capable of purifying graywater and providing year-round space conditioning with low-temperature heat as the primary energy input. The model is applied to 16 potential absorbents, and six are selected for parametric studies on desorber temperature, absorber temperature, condenser temperature, and heat sink temperature to determine the effects on the energy ratio (defined as the ratio of total useful output to total power input) of the cycle and the required graywater flowrate. Experiments are conducted to test the water flux and reverse solute flux in FO for the most promising absorbents. Of the six selected absorbents, four to two salt-organic mixtures and two pure salts appear to have the most promising thermodynamic behavior, while an ionic liquid demonstrates the best FO behavior.

Water Splitting with Enhanced Efficiency Using a Nickel-Based Co-Catalyst at a Cupric Oxide Photocathode

Homemade non-critical raw materials such as Ni or NiCu co-catalysts were added at the photocathode of a tandem cell, constituted by photoelectrodes made of earth-abundant materials, to generate green solar hydrogen from photoelectrochemical water splitting. Oxygen evolving at the Ti-and-P-doped hematite/TCO-based photoanode and hydrogen at the cupric oxide/GDL-based photocathode are separated by an anion exchange polymer electrolyte membrane placed between them. The effect of the aforementioned co-catalysts was studied in a complete PEC cell in the presence of the ionomer dispersion and the anionic membrane to evaluate their impact under practical conditions. Notably, different amounts of Ni or NiCu co-catalysts were used to improve the hydrogen evolution reaction (HER) kinetics and the overall solar-to-hydrogen (STH) efficiency of the photoelectrochemical cells. At −0.6 V, in the bias-assisted region, the photocurrent density reaches about 2 mA cm−2 for a cell with 12 µg cm−2 of Ni loading, followed by 1.75 mA cm−2 for the cell configuration based on 8 µg cm−2 of NiCu. For the best-performing cell, enthalpy efficiency at −0.4 V reaches a first maximum value of 2.03%. In contrast, the throughput efficiency, which is a ratio between the power output and the total power input (solar + electric) provided by an external source, calculated at −1.225 V, reaches a maximum of 10.75%. This value is approximately three times higher than the best results obtained in our previous studies without the use of co-catalysts at the photocathode.

Analysis and Output Power Control of Unidirectional Secondary-Resonant Single-Active-Half-Bridge DC-DC Converter

Development of high-frequency-isolated DC-DC converters is underway for charging and discharging electric vehicle batteries. As a charger, a Single Active Bridge (SAB) converter, which is composed of a primary full-bridge converter, a high-frequency transformer, and a secondary full-bridge diode rectifier circuit, has been proposed as a unidirectional high frequency isolated DC-DC converter. In this paper, as a simple circuit configuration, a Secondary-Resonant Single-Active-Half-Bridge (SR-SAHB) converter, in which the primary and secondary circuits of the SAB converter are both half-bridge circuits, and a resonant capacitor connected in parallel to each secondary diode, is created. Due to the partial resonance on the secondary side, power transmission with unity transformer turn ratio and unity voltage conversion ratio can be realized, and a high total input power factor of the transformer can be achieved. As a result, the maximum voltage and current of the switching devices and the transformer voltage can be reduced. Moreover, soft switching in all commutations can be realized. The operation waveform is analyzed, and output power control is derived using the variable frequency control method. The effectiveness of the proposed SR-SAHB has been verified by experimental results using a 2.4 kW 20 kHz, 265 V laboratory prototype.

8×40 Gbps WDM Amplification in a Monolithically Integrated Al2O3:Er3+-Si3N4 Waveguide Amplifier

On chip waveguide optical amplifiers have been extensively studied over the last years, with a wide variety of materials tested and proposed for different applications. Among the most prominent solutions for on-chip amplification, erbium doped waveguide amplifiers (EDWAs) are able to offer attractive performance metrics that can exceed SOA-based amplification solutions in traditional single and multi-channel systems. In this letter, we experimentally demonstrate a record high $8\times 40$ Gbps non return to zero (NRZ) wavelength division multiplexing (WDM) data amplification through a 5.9 cm long on-chip amplifier consisting of an erbium-doped aluminum oxide spiral waveguide monolithically integrated on the Si3N4 platform. Experimental results show more than 12.7 dB amplification per channel for low saturation total input power of −2.75 dBm, and clear eye diagrams and bit-error rate values below the KR4-FEC limit of $2\times 10 ^{-5}$ for all eight channels without any digital signal processing (DSP) applied to the signal to the receiver or transmitter side. The high losses from the fiber to chip interfaces, however, prevented achieving device net gain.

The Effect of Uneven Heating on the Flow Distribution Between Parallel Microchannels Undergoing Boiling

Abstract As the size, weight, and performance requirements of electronic devices grow increasingly demanding, their packaging has become more compact. As a result of thinning or removing the intermediate heat spreading layers, nonuniform heat generation from the chip-scale and component-level variations may be imposed directly on the attached microchannel heat sink. Despite the important heat transfer performance implications, the effect of uneven heating on the flow distribution in parallel microchannels undergoing boiling has been largely unexplored. In this study, a two-phase flow distribution model is used to investigate the impact of uneven heating on the flow distribution behavior of parallel microchannels undergoing boiling. Under lateral uneven heating (i.e., the channels are each heated to different levels, but the power input is uniform along the length of any given channel), it is found that the flow is significantly more maldistributed compared to the even heating condition. Specifically, the range of total flow rates over which the flow is maldistributed is broader and the maximum severity of flow maldistribution is higher. These trends are assessed as a function of the total input power, degree of uneven heating, and the extent of thermal connectedness between the channels. The model predictions are validated against experiments for a representative case of thermally isolated and coupled channels subjected to even heating and extreme lateral uneven heating conditions and show excellent agreement.

Performance testing and optimization of a split-type air conditioner with evaporatively-cooled condenser

In this study, the performance of a split-type air conditioner with evaporatively-cooled condenser was examined. The effect of evaporative cooling of the condenser on the performance parameters and energy efficiency were determined by comparing the results from an air conditioner with conventional type air-cooled condenser. Both systems were tested simultaneously for different ambient conditions. An optimization study were also performed to find out the optimal climatic conditions for the proposed system. The effects of outdoor temperature and relative humidity on both total power consumption and COP were discussed. With the evaporative cooling of the condenser of the split-type air conditioner, the COP increased by 10.2%–35.3%, and the cooling capacity increased by 5.8%–18.6%, while the total power consumption decreased by 4%–12.4%. The results showed that the outdoor relative humidity and temperature had a significant influence on the COP, cooling capacity, and total power input for split-type air conditioners with an evaporative condenser. The results of the optimization study showed that the optimal condition maximizing the COP of the proposed system was confirmed as higher outdoor temperature and lower relative humidity. For the total power consumption, however, the optimal condition was found as medium levels of the temperature and humidity. The effect of the outdoor temperature on the electricity consumption is larger than that of the RH, and this provides an opportunity of using the proposed system in a wide-range climatic conditions.

Application and limitations of inverted fireballs in a magnetron sputter device

In this paper the results of a first attempt to ignite an inverted fireball with a magnetron sputter source are presented. The conducted measurements show that there is no inverted fireball visible to the naked eye present during the experiments. However, some features are observed that indicate at least an initial onset of such an inverted fireball with an interruption before it is fully developed. In the course of the experiments magnetron sputtered molybdenum films have been deposited inside a highly transparent gridded anode and the obtained films have been analysed. It turns out that even without a visible inverted fireball being present, the film morphology and mechanical properties such as elastic modulus , hardness and surface roughness have changed significantly compared to a setup without inverted fireball anode. Additionally, the deposition rate is elevated by up to 20% inside the inverted fireball anode compared to the reference setup, although with a nearly threefold increase in total input power (cathode power + grid anode power). This increase in deposition rate was achieved despite the fact that a mesh electrode with only about 37% transparency was used. On the other hand, it was demonstrated that the use of additional gridded electrodes in such a device triggers instabilities and non-linearities in the plasma, which might be of interest for further fundamental research. • First attempt to ignite an inverted fireball in a magnetron sputter chamber • Indication of initial onset of an inverted fireball (IFB) • Enhancement of mechanical properties of Mo films by using IFB grid

Steric Effects on Space Electroosmotic Thrusters in Soft Nanochannels

The influence of steric effects on the performances of space electroosmotic thrusters (EOTs) was numerically delineated in soft nanochannels for which its walls are covered with polyelectrolyte materials. The size effect of the ionic species, namely the steric effect, is neglected in many previous research studies, but it has vital influences on electrostatic potential and electroosmotic velocity, which is further introduced into the present study in order to understand and improve the exploration of nano electroosmotic thrusters with soft channels. The thruster’s thrust, specific impulse, total input power, thruster efficiency and thrust-to-power ratio are computed based on finite difference methods. It is found that the thruster’s thrust and specific impulse increase with the steric parameter while the efficiency and thrust-to-power ratio possess opposite trends due to the enhancement of Joule heating dissipation. For real situations with the consideration of ion size, although the thruster’s thrust could be promoted, the efficiency is only 30–70%, and the peak values of thrust-to-power ratio fade away.

DC RAILWAY POWER FLOW ANALYSIS FOR ADDIS ABABA LIGHT RAIL TRANSIT USING NEWTON RAPHSON METHOD

This paper uses Newton–Raphson method for DC power flow analysis of the Addis Ababa light Rail Transit (AALRT). The study focuses onthe line section from Menilik II square station up to Lideta station. First the tractive effort required by the trains for different scenarios such as train movement in a straight line, a curved line, and a line with gradient is computed as the chosen line section contains all these scenarios. Then the total input power will be calculated using computed tractive effort obtained for each scenario and using other input parameters obtained from AALRT, and different papers. The input power for the different loads is computed, and the input power is used to analyse the bus voltage for different loads and train positions. Newton Raphson Method is used to solve the DC Power bus problem assuming that the train requires constant power while moving between two feeding stations. Even if using the rail as the return conductor for DC traction systems has economic advantages, it has some limitations like the rail potential and stray current. A rail potential study is carried out and conclusions are drawn. The result shows that the maximum voltage drop was 0.1 p.u and the train power consumption increases by 136.73 kW as the train takes a gradient of 3.92% and keep increasing again by 29.17kw with a curve resistance (100 meters). The Rail potential moves from 6.0139V to 29.85V proportionally with the variation of the total ground resistance.

Pemodelan dan Optimasi Multiobjektif Refrigerator Kompresi Uap Menggunakan Metode Meminimalkan Pembangkitan Entropi

The vapor compression refrigerators have many applications for cooling and freezing. The advantage of this system has good performance, and can meet the needs of a relatively large cooling capacity with a small system size. But behind its advantages, the energy consumption of this system is high so that energy saving is the main goal of optimization and this will continue to be done in a sustainable manner in the future. In this article, thermodynamic design optimization is presented to minimization entropy generation, minimization total power input, maximization the efficiency of the second law, and maximization the performance coefficient, simultaneously. A multi-objective genetic algorithm is used during the optimization process, and based on the Pareto frontier a decision-making strategy is obtained and then used to determine the final solution. The optimization results show that the method of minimization entropy generation can experience a paradox, where minimizing the entropy generation number of the system will not automatically result in the maximum efficiency of the second law but there is an optimal point which indicates that the generation of entropy is minimum. From the results of thermodynamic design optimization of the refrigerator, the total input power is 0.281 kW, the second law efficiency is 0.311 and coefficient of performance is 2.95.

A strip speaker using the traveling bending wave on a beam controlled by three actuators

The inherent weakness of conventional panel speakers is the inevitable multi-modal vibration behavior, resulting in severe fluctuation in the radiated sound spectrum, which is detrimental to the sound quality. A panel speaker that is actively controlled by array actuators at the panel edges has been proposed as a solution to the problem, but the increased cost and complexity due to a large number of actuators remain a challenge. In this study, a panel speaker using a thin beam, called a strip speaker, that adopts only three actuators is proposed to alleviate the modal fluctuation problem. When the middle position of the beam is excited by the primary actuator, the propagated bending wave field there from is controlled by two actuators at either end of the beam that prevents reflection of the wave. To achieve this, the inverse problem is derived by using the transfer function between the actuators and the coefficients of the reflected waves, from which an appropriate gain of the two control actuators is obtained as the inverse solution. For validation, a thin beam with a size of 315 × 40 × 2 mm3 is tested by simulation and experiment. Peaky resonant responses are made to disappear by controlling the vibration field, and the input mobility of the primary actuator becomes like that of an infinite beam. The boundary of the beam, which is newly defined at the location of the control actuators, is converted into an anechoic termination. The effect of the beam material is also tested by comparing aluminum and acrylic beams. It is shown that the damping of the acrylic beam is favorable in resulting a flat response, but its effective frequency range is lowered from that of the aluminum beam. In the experiment, the control actuators near the ends of unknown boundary conditions are located at the position to minimize the total input power for control. The experimental results of the controlled vibration field and radiated sound spectrum agree well with the predicted characteristics. It is shown that the proposed strip speaker with the traveling wave control method can be used to produce excellent acoustic performance.

Energy efficiency analysis of mass transport enhancement in time-periodic oscillatory electroosmosis

The streamwise mass transport of passive, neutral non-reacting solutes in oscillatory electroosmotic microchannel flows is theoretically investigated from an energy consumption and efficiency perspective for general asymmetric wall zeta potentials and slip velocities. Analytical solutions to the averaged mass transport and total power input (consisting of Joule heating, viscous dissipation, and sliding friction) are obtained and expressed in terms of the relevant parameters governing the system. Particularly, we define a “χg-parameter” to quantify the mass transport gained (excluding pure diffusion) per total power input in our analysis and discussions. While the no-slip, symmetric potential χg-performances agree with the mass transport results reported in previous literature, a “resonance like” behavior in the χg-performances is identified for large enough Womersley numbers and symmetric slip lengths despite the extra sliding friction, viscous dissipation, and Joule heating consumptions in the symmetric zeta potential configuration. When favorable asymmetries in the wall potentials and slip lengths are introduced, the χg-performances are not only considerably improved, but also highly correlated with the magnitudes of the velocity gradients in the oscillatory velocity profiles, hence reinforcing the physical picture of Taylor–Aris dispersion. Geometric symmetry can be identified among distinct velocity profiles which yield the same χg-performance. These profiles are generally associated with particular families of wall potential and/or slip length combinations also exhibiting symmetry among one another. Finally, the aspect ratio of the slit microchannel (width divided by length) is found to play a crucial role in significantly improving the χg-energy efficiency of mass transport in time-periodic electroosmosis.

ОЦЕНКА ВЛИЯНИЯ УПРАВЛЯЕМЫХ ЛЕСОВ НА БАЛАНС УГЛЕКИСЛОГО ГАЗА В АТМОСФЕРЕ ЗЕМЛИ

Technical energy costs required for forest cultivation, estimation of C-CO2 fluxes in model experiments with coniferous species of pine Pinus sylvestris L. and leaves species, natural form and gene modified clone of the ordinary aspen tree Populus tremula L., have been analyzed. At plantation cultivation of transgenic aspen clone with nitrogen fertilizers indirect costs of technical energy made up 85 % of total power input. A new three-stage method has been developed for assessing the impact of forests on the CO2 balance in the Earth's atmosphere. The final value of CO2 sink from the atmosphere at afforestation depends on the way wood is used.