Optimal Operation Conditions Research Articles

Research on square wave pulsed electrochemical phosphate recovery technology by Pt graphene foam metal electrode

Currently, using electrochemical precipitation techniques for phosphate removal and recovery in hydroxyapatite (HAP) or calcium phosphate (CaP) form is widely used, while the high energy consumption of electrochemical precipitation is a major obstacle to its application. In this study, a square wave pulsed electrochemical phosphate precipitation method was developed, which achieved phosphate pollution control and phosphate resource recovery and reuse at the same time. The square wave pulsed electrochemical phosphate recovery system was constructed and a Pt-rGO/CuF electrode was synthesized and evaluated. This result indicated that the Pt-rGO/CuF electrode had the highest electrocatalytic activity, the better electrical conductivity, and the smallest electron transport barrier. Under optimal operation conditions, the phosphate removal efficiency and specific energy consumption of Pt-rGO/CuF were 64.2% and 21.49 kWh kg−1, respectively. The Pt-rGO/CuF electrode demonstrated the best electrochemical precipitation reaction performance. The Pt-rGO/CuF electrode was applied to multiple types of actual wastewater, and the results showed that it has better application prospects in both low (7.75 mg L−1) and high (66 mg L−1) phosphate concentration wastewater, the phosphate removal efficiency was 75.5% and 59.1%, respectively. Compared with traditional chemical precipitation, the electrochemical precipitation method saved $2.88 per kg P and $57.57 per kg P, respectively.

Electrochemical Degradation of Diuron by Anodic Oxidation on a Commercial Ru0.3Ti0.7O2 Anode in a Sulfate Medium

This work presents the electrochemical degradation of the herbicide Diuron by anodic oxidation on a Ti/Ru0.3Ti0.7O2 metal mixed oxide anode using sulfate as the electrolyte. The study includes the influence of Diuron concentration and current density on anodic oxidation. The results evidence a first-order degradation, with the highest capacity achieved at 40 mA cm−2 and at an initial Diuron concentration of 38 mg L−1. Nevertheless, in terms of efficiency and energy demand, the operation at 10 mA cm−2 is favored due to the more efficient and less energy-consuming condition. To discern the optimum design and operation conditions, this work presents the results of a preliminary technical–economic analysis, demonstrating that, to minimize the total costs of the system, it is recommended to seek the most efficient conditions, i.e., the conditions demanding the lowest applied charges with the highest Diuron degradation. At the same time, attention must be given to the required cell voltage to not increase excessively the operating costs.

Study on polycyclic macromolecular drug solid stability: A case exploration of methylcobalamin

As one of derivatives of Vitamin B12, methylcobalamin (MeCbl) is an indispensable “Life Element” and plays an essential role in maintaining human normal physiology function and clinical medicine application. Because of the intricate molecular structure, strong hygroscopicity and optical instability, maintaining its solid stability is a great challenge in pharmaceutical preparation. Based on the structure features of MeCbl hydrates, this study explored the drug solid stability by designing solid-solid phase transformation (SSPT) experiments. Three hydrate powders of MeCbl that had special structure with isolated site and channel water molecules were discovered. It was found that drying condition and surrounding humidity were controlling factors influencing the final solid form. The inter-conversion relations relevant to heating-induced and humidity-induced structure changes were established among the three hydrate powders. Powder X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, high performance liquid chromatography and dynamic vapor sorption were used to characterize the differences and related properties of stably prepared MeCbl hydrate powders. The particle size of product could be regulated and controlled by optimizing operating conditions of crystallization process, where ultrasound-assisted and seeding-introduced were applied as promising strategies to enhance solution crystallization process. This study opens up the possibility for the stable preparation and large-scale production of polycyclic macromolecular bulk drugs like methylcobalamin.

Dimensionless Pressure Response Analysis for Water Supply Pipeline Systems with or without Pumping Station

Dimensionless governing equations of unsteady flow and solutions for the pipeline systems having a surge tank were developed. Frequency domain pressure response expressions for two widely used water supply systems were analyzed in dimensionless frequency and time domains. One is the simple reservoir pipeline surge tank valve system and the other is the pipeline system with pump and check valve protected by surge tank. Two different dimensionless expressions for the surge tank were developed and the performance of two expressions was compared. The frequency response pattern of impedance at the downstream valve indicated that the system resonance was determined by the lengths of the main pipeline and the connector and the locations of the surge tank and check valve for the protection of the pumping station. The difference between the simple pipeline system and that of a pump with a check valve was expressed in terms of the phase difference in frequency response distribution. The integrated pressure response for the protected pipeline section was evaluated considering the impact of surge protection in the frequency domain. A better understanding of system behavior can be obtained in terms of specific component isolation both in the frequency and time domain pressure responses. The driven responses in the frequency and time domain can be an important basis for optimum design and operation conditions of water supply systems in dimensionless space.

Response surface methodology (RSM) for optimizing ozone-assisted process parameters for formaldehyde removal.

Formaldehyde, a volatile organic compound (VOC), is one of the main gaseous pollutants from commercial cooking. The present study evaluated the effectiveness of a laboratory-scale ozone-assisted indirect plasma method for formaldehyde removal using response surface methodology (RSM). A dielectric barrier discharge (DBD) reactor was used for ozone generation. Inlet HCHO concentration, ozone concentration, and residence time were considered the design parameters, and formaldehyde removal efficiency (response 1) and energy yield (response 2) were considered response parameters. The optimized models showed a positive correlation between the predicted and experimental outcomes. Inlet ozone concentration, the most significant parameter in the removal efficiency model, represented a positive correlation with this response in most parts of the operating region. The optimal point with the highest desirability (i.e., D1 point) was obtained at the inlet HCHO concentration of 120ppm, inlet ozone concentration of 40ppm, and reaction time of 11.35s within the parameter ranges studied, resulting in 64% removal efficiency and 2.64g/kWh energy yield. At the point with the second highest desirability (D2), 100% removal efficiency along with 0.7g/kWh energy yield was achieved indicating the very good performance of the process. The indirect plasma approach used in this study presented a successful performance in terms of removal efficiency along with acceptable energy yield compared to other plasma-assisted processes reported in the literature. The results suggested that ozone-assisted indirect plasma treatment can be utilized as an efficient alternative method for formaldehyde removal in commercial kitchens, while efficiency or energy yield should be prioritized for optimizing operating conditions.

Investigation of the oxy-fuel combustion process in the full-loop circulating fluidized bed

Oxy-fuel combustion of fossil fuels in circulating fluidized bed (CFB) reactors has been widely implemented in various industries. However, the knowledge of complex gas thermal characteristics (e.g., gas temperature, viscosity, density, conductivity and specific heat capacity) is still in lack. Understanding the distribution of these gas thermal properties within the oxy-fuel combustion CFB reactor is crucial for predicting particle behavior, optimizing operating conditions, and performing design optimizations. In this study, the hydrodynamics and thermochemical characteristics of dense reactive flow in a 0.1 MWth pilot-scale CFB are simulated via a developed multi-phase particle-in-cell (MP-PIC) reactive model. The impacts of some key operating parameters on the gas thermal properties, gas species distribution and gas-solid flux are studied. The results show that the dynamics and thermochemical variables of gas-solid flow show non-uniform distributions in the riser due to the segregation mechanism and lateral injection of solid fuels. Combustible gases (e.g., CH4, CO, H2, and H2S) mainly concentrate in the left area of the riser. Enlarging the oxygen concentration increases gas viscosity while decreases gas density. The density of gas phase ranges from 0.35 kg/m3 to 0.50 kg/m3 while gas turbulent viscosity ranges from 4.2 × 10−5 m2/s to 4.8 × 10−5 m2/s.

Electrochemical cell design and performance evaluation of polyvinyl ferrocene/carbon nanotube electrodes for selective formate separation

Selective ion separation is a fundamental challenge with applications ranging from the manufacturing of pharmaceuticals & industrial salts to water desalination. In particular, the separation of formate, a primary product of electrochemical carbon dioxide reduction, has attracted attention not only to reduce carbon emissions and energy costs but to provide new routes to value-added chemicals. In the present study, selective formate separation from an aqueous solution is demonstrated using an electrochemical flow cell with symmetric redox-active polyvinyl ferrocene electrodes. An electrosorption system equipped with an electrosorption cell, inline conductivity, and pH sensors was constructed to provide real-time measurements of the formate adsorption performance in continuous flow mode while varying operating conditions such as the flow rate, cell voltage, and electrolyte concentration. These parameters were optimized using a Box–Behnken experimental design to improve the formate adsorption selectivity. The flow cell results showed a selectivity higher than 6.0 toward the removal of formate in an electrolyte containing a 30-fold excess of perchlorate under optimal operation conditions (i.e., 0.5 mL/min flow rate, 1.0 V, and 15 mM electrolyte concentration). The performance of the flow cell was also tested using a solution that contained different liquid CO2 reduction products, and formate separation was achieved. The results suggest that the proper design of the electrochemical cell and efficient operation of the flow platform pave the way for scaling up the technology for selective formate separation.

Hydrogen production from an on-board reformer for a natural gas engine: A thermodynamics study

In the present study, for an insight into the optimizing windows of comprehensive energy efficiency for open-loop system of marine NG engine and reformer, a peculiar thermodynamic equilibrium model for simulating the exhaust gas-fuel reforming process is established using equilibrium constant and experimental results. The accuracy of the model is evaluated by comparing numerical simulations with data derived from experiment of the open-loop operation system. Accordingly, the effect of engine loads and excess air (λ) as well as reformer feedstocks on maximum theoretical reforming characteristics are investigated. In addition, the energetic distribution in open-loop operation system can be clarified by the first law of thermodynamic. The results shown that fuel conversion toward H2 is highly selective due to the enhancement of reaction temperature with increasing engine loads. Especially, under 75% engine load, the maximum theoretical H2 yield reaches up to approximately 42.3% when λ = 1.4, CH4/O2 (M/O) = 1.5 and H2O/CH4 (S/M) = 2; The high λ will dilute the feed concentration of the reformer, thereby inhibiting the reforming reaction moving toward H2 production. Hence, an appropriate λ (1.4) can maximize the hydrogen production capacity of the reformer. In addition, according to the energy distribution of the open-loop system, the theoretical reforming energy efficiency of the reformer reaches a peak of 93.5% at S/M = 2 and M/O = 5. However, it can be found that M/O should be maintained above 1.5 to acquire optimal reforming energy utilization efficiency of system. Summarily, the optimal operation conditions for the reformer in open-loop operation system are confirmed: M/O = 1.5–2.5 and S/M = 1.5–2 under 75% engine load, which could fulfill efficient reforming performance.

Preparation, characteristics, and performance of the microemulsion system in the removal of oil from beach sand

Oil deposited on shoreline substrates has serious adverse effects on the coastal environment and can persist for a long time. In this study, a green and effective microemulsion (ME) derived from vegetable oil was developed as a washing fluid to remove stranded oil from beach sand. The pseudo-ternary phase diagrams of the castor oil/water (without or without NaCl)/Triton X-100/ethanol were constructed to determine ME regions, and they also demonstrated that the phase behaviors of ME systems were almost independent of salinity. ME-A and ME-B exhibited high oil removal performance, low surfactant residues, and economic benefits, which were determined to be the W/O microstructure. Under optimal operation conditions, the oil removal efficiencies for both ME systems were 84.3 % and 86.8 %, respectively. Moreover, the reusability evaluation showed that the ME system still had over 70 % oil removal rates, even though it was used six times, implying its sustainability and reliability.

Investigation into the operation of an autothermal two-section subbituminous coal fluidized bed gasifier

Using a newly developed experimental setup, the features and advantages of an autothermal single-casing atmospheric subbituminous coal fluidized bed air-blown gasifier, combining a combustion and gasification section, and mixing the dispersed phase (inert material, char) and heat exchange between them through an annular transfer device, have been revealed. To increase the efficiency of the gasifier, an experimental-computational method was developed find the conditions for optimal operation, combining changing the annular flow’s geometry and regulating the primary air for gasification. A simple and reliable multizone thermodynamic calculation model makes it possible to predict the composition of char and syngas in the gasification section with acceptable accuracy. This method confirmed that a two-section fluidized bed gasifier can provide efficient gasification of solid fuels and is suitable for use in small-scale cogeneration plants. Syngas with a heating value of 3.6–4.5 MJ/m3 and CGE of 38.2%–42.3% was obtained in the experimental setup without optimizing the primary air flow rate. With optimization, the indicators increased to the heating value of syngas of 5.20–5.34 MJ/m3 and CGE of 42.5%–50.0%. With heat regeneration of 0.8, CGE increases to 70%.

LiNixMn2-xO4 for multicycle electrochemical selective recovery of lithium from lithium-ion battery leachate

Lithium (Li) has been known for possessing excellent electrochemical performance due to its growing use in energy-related applications such as lithium-ion batteries (LIBs). End-of-life LIBs are usually recycled through a leaching process that yields a solution known as LIB leachate that contains lithium and other LIB materials. The electrochemical technique, which generally uses lithium-manganese oxide (LMO) electrodes, is one of the promising techniques for selectively recovering lithium from the LIB leachate. However, the stability performance of LMO is poor, mainly due to the Jahn-Teller effect of Mn3+ in LMO. In this study, substituting with nickel dopant was used to reduce the manganese content of LMO. Lithium was selectively recovered from actual LIB leachate using lithium nickel manganese oxide (LNMO) and activated carbon (AC) electrodes. The effects of operation time and current on lithium recovery from LIB leachate were studied to determine the optimal operation condition. It was discovered that longer operation time and higher current increased lithium adsorption capacity and energy consumption. Lithium recovery using the obtained optimal operation conditions resulted in a lithium adsorption capacity of 1.58 mmol/g, a lithium purity of 95.22 %, and an energy consumption of 2.79 Wh/mol. The effect of nickel doping into LMO on its performance was also investigated over 20 cycles. In a 20-cycle lithium recovery test, LiNi0.5Mn1.5O4 (LNMO-0.5) electrode showed stable lithium recovery performance until the 20th cycle, retaining approximately 97 % of the initial lithium adsorption capacity and increasing energy consumption by approximately 7 % after 20 cycles. Meanwhile, for pristine LMO, after 20 cycles, only about 47 % of the initial lithium adsorption capacity was retained, and the energy consumption was approximately 65 % higher than the initial cycle. Due to the outstanding performance of LNMO, it is expected to be a potential material for long-term selective lithium recovery from leachate in actual lithium-ion battery applications.

Cost-Effective Processes for Denim Production Wastewater: Dual Criterial Optimization of Techno-Economical Parameters by RSM and Minimization of Energy Consumption of Photo Assisted Fenton Processes via Direct Photovoltaic Solar Panel Integration

Denim production wastewater is an industrial wastewater with a high organic pollutant content. The aim of this study was to improve a cost-effective method via solar panel integration to the photo Fenton process (PFP) and photo electrochemical Fenton process (PEFP) for removing high chemical oxygen demand (COD) from denim production wastewater. To determine process parameter values, the double criterial optimization option was used. The results that maximized the COD removal efficiency and minimized the operating cost of two oxidation processes were determined by response surface methodology (RSM). Optimum operation conditions for the PFP process were 3.18 initial pH, 2.3 g/L Fe2+ concentration, and 27 g/L H2O2 concentration while they were 3.00 initial pH, 27.06 A/m2 current density, and 28.16 g/L H2O2 concentration for PEFP. At the optimum conditions, COD and the total organic carbon (TOC) removal efficiency of PFP were 85% and 61%, respectively. They were determined as 90% and 73% in PEFP. Carbon oxidation state (COS) and average oxidation state (AOS) parameters were used to obtain the biodegradation capability of organic materials. The biodegradability capability of wastewater was observed as high after the Fenton processes. As a result of the optimization of technical parameters, total operating cost was obtained as USD 14.62/m3 (USD 4.25/kgCODremoved) in PFP and USD 13.79/m3 (USD 3.73/kgCODremoved) in PEFP. After the integration of the photovoltaic solar panel to the processes, the total operating cost of PFP and PEFP decreased in a ratio of 61% and 64%, respectively.

Application of improved particle swarm optimization in the energy saving strategy for a central air‐conditioning system

AbstractHere, a new energy‐saving optimization method, known as the Improved Particle Swarm Optimization (IPSO) algorithm, is proposed to solve the practical engineering problem of high energy consumption during the operation of central air‐conditioning water systems. The mathematical model of total energy consumption optimization and the calculation principle of the IPSO are established. It is shown via experiments that the proposed algorithm requires a short optimization time and can achieve the optimal operation conditions of water systems under various cooling loads, where these conditions include the optimal control strategy of equipment, and water temperature at the inlet and outlet of chillers. Furthermore, it ensures the lowest energy consumption of water system operation. The measured results show that the comprehensive energy saving rate of water system operation can reach more than 18% compared with that before the system transformation.

Evaluation and comparison of hydrogen production potential of the LIFE fusion reactor by using copper–chlorine (Cu–Cl), cobalt–chlorine (Co–Cl) and sulfur–iodine (S–I) cycles

In this paper, the hydrogen production and neutronic analysis of the Laser Inertial Confinement Fusion-Fission Engine (LIFE) fusion reactor have been analyzed. The potential of hydrogen production from unit integrated of the reactor with three different hydrogen production methods which has copper-chlorine (Cu–Cl) cycle, cobalt-chlorine (Co–Cl) cycle and sulfur-iodine (S–I) cycle have been investigated. Neutronic performance analysis for various parameters was calculated statically by using Monte Carlo N-Particle Nuclear Code and determined optimum reactor operation conditions. The hydrogen production potential for all conditions was investigated as statically. And also, the production potential with determining optimum conditions was performed over operation plant. Tristructural isotropic (TRISO) coated thorium carbide (ThC) was used as fuel of LIFE fusion reactor. Natural lithium and FLiNaBe (LiF + NaF + BeF2) were used first and second coolant, respectively. In the statistical analysis, effects of ThC fuel ratio, 1st and 2nd coolant zone thicknesses were examined. As a consequence of the neutronic analysis, tritium breeding values and energy multiplication values (M) was attained and according to M values, hydrogen production amount, required thermal power and thermal power ratios were acquired. Among the used hydrogen production methods, Cu–Cl cycle produced the highest hydrogen amount, while the Co–Cl cycle has the lowest H2 amount. At the end of the reactor operation time for determining optimum conditions, the produced hydrogen amounts are 9.00, 4.80 and 7.36 kg/s for Cu–Cl, Co–Cl and S–I cycles, respectively.

COMPARISON PROCESS OF SOLVENT-FREE MICROWAVE EXTRACTION AND MICROWAVE HYDRO-DISTILLATION METHODS IN ESSENTIAL OIL PRODUCTION FROM CABBAGE ROSES FLOWER (Rose × centifolia)

Indonesia has many diverse natural resources that still cannot be utilized optimally such as the extraction of essential oil from Cabbage Roses flowers (Rose × centifolia). This study compares the extraction amendments, extraction time, and essential oil composition of fresh rose flowers obtained by the Solvent-Free Microwave Extraction (SFME) method to those obtained using the Microwave Hydro-Distillation (MHD) extraction method. Optimum conditions using the same amount of raw material in this study for the MHD method optimum conditions of operation: time of 90 minutes; the ratio of 1 g/mL; the power of 450 W, obtained a yield of 0.152% and SFME method optimum conditions of operation: time of 90 minutes, ratio 0.2 g/mL; power 450 W, obtained a yield of 0.358%. Electricity consumption to obtain 1 g of rose essential oil extracted using the MHD method is 4.087 kWh, while for the SFME method, it is 1.073 kWh. So it can also be said that the MHD method requires electricity consumption which is 3.8 times higher when compared to the SFME method.

Bioconversion of CO2 and potential of gas fermentation for mainstream applications: Critical advances and engineering challenges

AbstractThe undesirable consequences of climate change are attributed to the ever‐increasing emissions of greenhouse gases, especially carbon dioxide. For the sustainable development of human society, there is an urgent need to develop novel techniques for efficient conversion and utilization of carbon dioxide. Hence, carbon capture and storage, artificial bioconversion of carbon dioxide are topics of great interest for current researchers across the globe. Here, we elucidate the different techniques of carbon fixation, which fall under the broad categories of natural fixation pathways, thermo‐catalytic conversion techniques, and synthetic carbon fixation pathways. Based on a comparative analysis, gas fermentation is a promising method for the microbial conversion of CO2‐containing gases into fuels and chemicals. However, for mainstream applications, in‐depth reviews of different reactor configurations and the various engineering aspects related to process development are still lacking. We have analyzed the published literature relating to artificial bioconversion of carbon dioxide and focused on the factors like equipment selection and reactor design that can assist in scale‐up of gas fermentation technology. The review provides an in‐depth understanding of engineering aspects related to stirred tank and bubble column reactors, focusing on the technical design parameters and discussing the conditions for optimal operation and performance during commercial gas fermentation processes.

An intuitionistic fuzzy linear mathematical model to determine the hybrid manufacturing system’s optimal operation condition

The recycling of the used products collected by the manufacturing companies for recycling from their customers and their inclusion in the production system for remanufacturing has become an essential topic regarding sustainable production systems. Using parts and equipment in the remanufacturing system, especially in electronic products and products in the automotive sector, is preferred because of the opportunities to reduce costs and increase energy and workforce efficiency. In this article, we analyzed the management of a hybrid production system that processes new or returned materials in the manufacturing system. An intuitionistic fuzzy linear mathematical model is developed to demonstrate financial benefit and make decisions about using used parts in remanufacturing systems. Our study contributes to the literature by first adapting the magnitude function to the hybrid manufacturing and remanufacturing process optimization problem. Also, the innovative scope of the paper is expanded by applying IVITFN to the remanufacturing process optimization problem for the first time using comparative analysis. We consider relevant costs, the uncertainty about the number of returned products, demand, unit costs and unit production times, and capacity limitation in determining the optimal operation condition. The proposed model results show smaller cost values against other models in the literature.

Exergoeconomic Analysis and Tri-Objective Optimization of the Allam Cycle Co-Fired by Biomass and Natural Gas

Abstract Allam cycle is known as an oxy-fuel gas-powered power cycle. A modified Allam cycle co-fired by biomass and natural gas is proposed in this paper, evaluated, and optimized. Detailed thermodynamic, economic, and exergoeconomic analyses are reported for the co-fired cycle. And parametric analysis and a tri-optimization are carried out to investigate the effects of cycle variables on the system performance. The results show that as the co-firing ratio increases from 20% to 100%, the exergetic efficiency and the levelized cost of electricity vary from 44.3% to 36.8% and 123.2 $/MWh to 164.4 $/MWh, respectively, while the specific negative CO2 emission increases from 44.5 kg/MWh to 251 kg/MWh. The results of tri-objective optimization reveal that the highest exergetic efficiency of 46.85%, lowest levelized cost of electricity of 99.57 $/MWh, and highest specific negative CO2 emission of 323.6 kg/MWh are obtained respectively at different optimal operation conditions.

Benchmarking Thermodynamic Models for Optimization of PSA Oxygen Generators

In this review, the authors conducted benchmarks for three thermodynamic models to analyze PSA-based medical oxygen concentrator (MOC) systems to allow for optimization and operational flexibility. PSA oxygen generator plants are good medical-grade oxygen sources, a crucial tool in healthcare from the primary to the tertiary level. However, they must be designed accordingly and properly operated, considering key design goals such as improving adsorbent productivity, improving oxygen recovery, and innovating to reduce unit size and weight. The importance of mapping the performance of various design and operating requirements or designs themselves on outlet product specifications and production effectiveness is outlined. Emphasizing optimal PSA design and operation, the authors suggest considering simulation-based optimization frameworks or high-fidelity modeling for the optimal layout and operation conditions of adsorption-based MOC systems. Notwithstanding, a simplified first-principles-based model with additional assumptions and simplifications generates a large volume of scenarios faster. Therefore, it represents a good approach for a feasibility study dealing with many options and designs or even the real-time monitoring of PSA operating conditions. All this paved the way for efficient translation into machine learning models and even deep learning networks that might be better suited to simulate the complex PSA process. The conclusion outlines that PSA-based plants can be flexible and effective units using any of the three models when properly optimized.

Wireless Powering Efficiency of Deep-Body Implantable Devices

The wireless power transfer efficiency to implanted bioelectronic devices is constrained by several frequency-dependent physical mechanisms. Recent works have developed several mathematical formulations to understand these mechanisms and predict the optimal operating conditions. However, existing approaches rely on simplified body models, which are unable to capture important aspects of wireless power transfer. Therefore, this paper proposes the efficiency analysis approach in anatomical models that can provide insightful information on achieving the optimum operation conditions. First, this approach is validated with a theoretical spherical wave expansion analysis, and the results for a simplified spherical model and a human pectoral model are compared. The results show that although a magnetic receiver outperforms an electric one for near-field operation and both sources could be equally employed in far-field range, it is in mid-field that the maximum efficiency is achieved with an optimum frequency between 1-5 GHz depending on the implantation depth. The receiver orientation is another factor that affects the efficiency, with a maximum difference between the best and worst-case scenarios around five times for the electric source and over 13 times for the magnetic one. This approach is used to analyze the case of a deep-implanted pacemaker wirelessly powered by an on-body transmitter and subjected to stochastic misalignments. We evaluate the efficiency and exposure, and we demonstrate how a buffered transmitter can be tailored to achieve maximum powering efficiency. Finally, design guidelines that lead to optimal implantable wireless power transfer systems are established from the results obtained with the proposed approach.