Mechanical Energy Recovery Research Articles

The Effect of a Wearable Assistive Trunk Exoskeleton on the Motor Coordination of People with Cerebellar Ataxia

The motor features of people with cerebellar ataxia suggest that locomotion is substantially impaired due to incoordination of the head, trunk, and limbs. The purpose of this study was to investigate how well a wearable soft passive exoskeleton worked for motor coordination in these patients. We used an optoelectronic system to examine the gait of nine ataxic people in three different conditions: without an exoskeleton and with two variants of the exoskeleton, one less and the other more flexible. We investigated kinematics using trunk ranges of motion, the displacement of the center of mass in the medio-lateral direction, and the parameters of mechanical energy consumption and recovery. Furthermore, we investigated the lower limb and trunk muscle coactivation. The results revealed a reduction of the medio-lateral sway of the center of mass, a more efficient behavior of the body in the antero-posterior direction, an energy expenditure optimization, a reduction of muscle coactivation and a better coordination between muscle activations. As a result, the findings laid the groundwork for the device to be used in the rehabilitation of individuals with cerebellar ataxia.

Исследование математической модели объемного гидропривода с релейным управлением применительно к грузовой лебедке крана

The known variants of volumetric hydraulic drives of lifting and technological mechanisms are considered and analyzed. The areas of application of pumping and accumulator hydraulic drives, with various types of regulation, and options for their implementation as drives of a cargo winch of a bridge crane are considered. It is shown that the operation of the volumetric hydraulic drives of the cargo winch, along with volumetric and throttle control, can be performed by a relay method. It is noted that the cyclical operation of lifting mechanisms during lifting and lowering of cargo allows for mechanical and hydraulic energy recovery within the working cycle, which is a promising way to significantly increase the efficiency of their work. The analysis of the existing designs of hydraulic drives of technological machines, allowing to recover the potential energy of working bodies with cargo, is carried out. It is proposed as an alternative to the known hydraulic drives of the cargo winch of the bridge crane, a hydraulic drive with relay control. The efficiency of such a drive is shown, according to the indicators of the nominal pressure utilization coefficient and the energy intensity of the working fluid, in the case of the implementation of mechanical and hydraulic energy recovery in the working cycle in it. The mechanical and hydraulic circuits of such a drive are examined. An algorithm of mathematical model of its operation with consideration of different phases of cargo movement is proposed and its investigation is carried out. The possibility of fulfilling the safety conditions of operation of a hydraulic drive with relay control, in terms of ensuring the requirements for the uniformity of cargo movement, is analyzed.

Experimental platform for studying energy regeneration in electric vehicle powertrains

Investigation into the energy consumption in electric vehicles (EVs) plays a pivotal role in determining their autonomy and assessing the electric system performance across diverse operational scenarios. This study focuses on the concept of energy regeneration, encompassing the recovery and storage of kinetic mechanical energy during braking or descent in EVs. Employing control systems in power electronics becomes necessary to establish a seamless workflow across operational quadrants to ensure efficient energy regeneration in an electric machine functioning as both a motor and a generator. To seamlessly integrate new technologies into practical applications, it is essential to conduct thorough evaluations in laboratories prior to deployment. This paper introduces an experimental platform specifically designed to analyze energy consumption and storage in EVs by emulating their powertrains in a controlled laboratory environment. The platform comprises key components for emulating the powertrain of a single-motor electric vehicle with single-axle traction, including a power converter configured in two quadrants, an energy storage system, a primary rotating electric machine, and a mechanically coupled point load torque (another motor). This paper provides a detailed guide on implementing such a laboratory and for facilitating the testing of diverse motor technologies and controllers under varied operational conditions. This comprehensive approach allows for the assessment of electromechanical system efficiency, focusing on both energy recovery and comprehensive control of electric power converters. Validation tests conducted under urban conditions and on steep terrains demonstrate the effectiveness of the platform in analyzing the energy efficiency of both the induction machine and the power controller.

Research on Energy Recovery System

As the number of electric vehicles continues to grow globally, more and more advanced technologies are being applied to electric vehicles. Energy recovery technology is a crucial part of them. The basic principle of how electric vehicles work is to convert chemical energy into electrical energy, and then convert electronic energy into kinetic energy. Actually, the ability of deceleration is necessary for electric vehicle. However, large amount of energy may lose due to this period. So, people developed energy in order to recover this energy.This study contain the introduction of two different types of energy recovery system, electronic energy recovery system and mechanical energy recovery system. Including two major advancements in this field in recent decades which contribute a lot in electronic recovery system. In addition, I introduced some latest research on mechanical energy recovery system which utilized hydro-mechanical technology. Most of my analysis are based on ECE (European standard operating conditions) . Worth noticing that more areas for expansion of this technology are also mentioned in my essay such as rotorcrafts and motor-driven tanks which are the latest products.

Analytical Study on Mechanical Energy Recovery and Utilization of New Energy Vehicles

The pursuit of energy efficiency and sustainability in the automotive industry has become increasingly urgent in response to growing environmental concerns. Herein, this paper focuses on the critical challenge of energy dissipation in new energy vehicles, particularly during braking and suspension vibrations. The paper presents two innovative energy recovery solutions aimed at reducing energy losses and enhancing sustainability. In the realm of sustainable transportation, this study critically evaluates the optimization strategies for braking energy recovery in new energy vehicles. A key recommendation is the integration of a permanent magnet synchronous motor combined with an advanced fuzzy control system. Such an amalgamation not only heightens energy efficiency but also substantially extends the driving range of electric vehicles. Beyond braking energy, the research casts light on an often-overlooked energy source: the vibrational energy from vehicle suspensions. By introducing an innovative electromagnetic damper design coupled with the strategic incorporation of piezoelectric materials, the study unveils avenues to both improve suspension dynamics and transform vibrational energy into usable electrical power. While there are current technological and economic challenges, the ongoing innovations in the design and control processes of new energy vehicles highlight the profound potential within this domain. The insights offered in this context further emphasize the critical need to expand the horizons of sustainable transportation design and management approaches.

The effect of total ankle arthroplasty on mechanical energy exchange

Total ankle arthroplasty (TAA) is a common surgical solution for patients with debilitating arthritis of the ankle. Prior to surgery patients experience high levels of pain and fatigue and low mechanical energy recovery. It is not known if TAA restores healthy levels of mechanical energy recovery in this patient population. This study was designed to determine whether mechanical energy recovery was restored following TAA. Ground reaction forces during self-selected speed walking were collected from patients with symptomatic, unilateral ankle arthritis (N = 29) before and one and two years after primary, unilateral TAA. The exchange of potential (PE) and kinetic (KE) energy was examined, and direction of change (%congruity) and energy exchange (%recovery) between the two curves was calculated, with those subjects with low congruity experiencing high energy recovery. Linear regressions were used to examine the impact of walking speed, congruity, and amplitude of the center of mass (COM) displacement on %recovery, while ANOVA and ANCOVA models were used to compare energy recovery and congruity across the three time points. Gender, BMI, and age at surgery had no effect in this study. TAA improved walking speed (p = 0.001), increased energy recovery (p = 0.020), and decreased congruity (p = 0.002), and these levels were maintained over at least two years. Differences in congruity were independent of walking speed. In some patients, especially those who are severely debilitated by ankle arthritis, TAA is effective in restoring mechanical energy recovery to levels similar to an asymptomatic population of a similar age recorded by other studies.

Beakiation: how a novel parrot gait expands the locomotor repertoire of living birds.

Occupation of arboreal habitats poses myriad locomotor challenges, driving both anatomical and behavioural innovations across various tetrapod lineages. Here, we report and biomechanically assess a novel, beak-driven locomotor mode-'beakiation'-by which parrots advance along the underside of narrow arboreal substrates. Using high-speed videography and kinetic analyses, we describe the limb loading patterns and pendular mechanics of beakiation, and compare the biomechanical characteristics of this gait with other suspensory behaviours (namely, forelimb-driven brachiation and inverted quadrupedal walking). We report that the parrot beak experiences comparable force magnitudes (approx. 150% body weight in the normal plane; approx. 50% body weight in the fore-aft plane) to the forelimbs of brachiating primates. Parrot beakiation is also characterized by longer-than-expected pendular periods, similar to observations of gibbon brachiation. However, in terms of mechanical energy recovery, beakiation is typified by lower levels of energetic recovery than brachiating specialists: a product of its slower, more careful nature. The observation of this novel behaviour-which adds to a growing base of literature regarding beak-assisted locomotor strategies in birds-highlights the extraordinary behavioural plasticity of birds, the functional versatility of the avian beak, and the difficulties in reconstructing an animal's locomotor repertoire from morphological characteristics alone.

ANALYSIS OF CONSTRUCTIONS OF RECEIVED AMORTIZATION SYSTEMS

The theoretical research is devoted to the improvement of the existing structures of shock absorbers, which ensure the recovery of mechanical energy into electrical energy with further useful use. First of all, an analysis of the use of different shock absorbers by drive type was performed. The advantages and disadvantages of each of them are established according to the criterion parameters of reliability, manufacturability and operation. A refined classification of shock absorbers by type of kinematic connection and structural design is proposed. According to the proposed classification, the rational type of drive for creating new models of recuperative shock absorbers is determined to be hydraulic. According to the developed recommendations for choosing the shock absorber drive type, you can choose the drive type depending on the desired prevailing technical indicator. The paper presents the results of a theoretical study of existing designs of recuperative damping systems. It has been established that, in addition to energy recovery, such damping systems provide improved damping and damping performance and allow the user to choose the desired mode of operation of the suspension. Analysis of existing designs of regenerative shock absorbers indicates better efficiency of systems with feedback. This type of communication is provided in most cases by using electronic measuring systems with a control unit, which greatly complicates and increases the cost of the design. Based on the results of the theoretical analysis of the existing designs of recuperative shock absorbers of world manufacturers and developers, technical and technological requirements for new designs of recuperative shock absorbers were formed, which, in our opinion, are aimed at rationalization and optimization of the latter. According to the developed technical and technological requirements, a basic design scheme of a recuperative damping system with hydrovalves for improving quality parameters was developed. The principle of operation of the quality valve with a profiled spool window is described

Agricultural Plastic Waste Management

This article aims at describing both the studies and results implemented in the framework of the H2020-EU research project “RECOVER: New bio-recycling routes for food packaging and agricultural plastic waste” which deals with the sustainability of innovative biodegradation processes for plastic waste and production, in any environmental, social, economic and safety matters. In such a framework, the POLOG University Centre (Livorno, Italy), reconstructed and analyzed the actual farm plastic waste supply chain, as described in the following sections. The first section is introductive and it has been intended as a primer to the most common different types of plastic materials. The second section has deserved to be a state of the art on the most relevant issues raised in plastic waste management. The third section deals with suitable approaches to address the environmental side effects of rapidly growing plastics production, use, and disposal. Some of these approaches were listed, such as physical treatment of the polymeric components, plastic reduction use and employment as much as mechanical and/or chemical recycling and energy recovery. The fourth section shows how some of the above main issues, which raise coping with plastic reduction and recycling, are suited to be coped with from a logistics perspective. Such logistics belong to the basic needs due to tackling any plastic waste supply chain, i.e. collection and transport to intermediate stock and final delivery to recycling plants and/or brownfields, applying the set of methodologies and techniques drawn from the well-known field of pick-up-anddelivery models. These last tasks become crucial when the main effort has addressed the enforcement of any feasible changes from the use of items made in old high environmental intrusive to their replacement with new agricultural and biodegradable plastics. The paper goes to end presenting shortly of a few suitable solutions that could be proposed and applied to the entire plastic waste supply chain. Finally, some concrete aspects of each phase of the supply chain were discussed and it was highlighted how much each of these can be best used in addressing the problem known throughout the world as the problem of the emergency of old plastic waste.

New configuration to improve the power input/output quality of a superconducting energy storage/convertor

In the last few years, we have proposed a new kind of superconducting energy storage/convertor and conducted a number of investigations on it. The results of these studies demonstrate this kind of device is of significant advantages in mechanical → electromagnetic → mechanical energy conversion. In this study, we proposed a new configuration for this kind of device, which consists of two permanent magnets and two superconducting coils. With the new configuration, the evenness of the power distribution of this kind of device in energy converting can be greatly improved compared to the original single magnet and single superconducting coil configuration. As a result, the energy storage capacity is also increased. We carried out theoretical analysis and numerical derivation which delivered mathematic descriptions on the parameters of new configuration. Then, experiments were conducted on a prototype with the new configuration. The experimental results of the key parameters showed good agreement with the calculated ones. Furthermore, we investigated the critical factors impacting the power distribution of this kind of device, including the ratio of the magnetic moments of the two magnets and the distance between the two superconducting coils. It has been proved that for any given distance, a definite magnetic moments ratio can always be obtained, resulting in the optimum power performance of the proposed configuration. The study further proves the application feasibility of this kind of energy storage/convertor in mechanical energy recovery and reuse.

Plastic Recycling Feasibility with the Triple-Layered Business Model Canvas

The massive consumption of plastic material and its waste worldwide has made it necessary to find alternative solutions to reduce the size of landfill areas and recover their energy content. Pyrolysis is one of the chemical recovery technologies for plastics whose return on investment is estimated between 16% and 21%. This article aims to use the Triple Layer Business Model Canvas tool, which considers the elements of a business model visually and dynamically based on the three pillars of sustainability (economic, environmental, and social). This approach allowed for a comprehensive analysis of the sustainability-oriented business model. As a result, we concluded that pyrolysis is viable as a complementary process to other means of mechanical recycling and energy recovery.

MATHEMATICAL MODEL OF THE MOVEMENT OF A LOW-TONNAGE TRUCK WITH A MECHANICAL ENERGY RECOVERY UNIT

To date, an important role in many areas of economic activity is played by road freight transport. First of all, it depends on how quickly and reliably the goods will be delivered from one place to another. With an extensive list of various goods that need to be transported, there is no less a large selection of vehicles to perform these tasks.
 Due to the fact that heavy trucks are currently prohibited from entering most cities, low-tonnage trucks, including vans and trucks of the transport category “N1”, have become in demand. Their main purpose is the transportation of small shipments within the city or over relatively short distances.
 Low-tonnage trucks should have not only high dynamic characteristics, but also low fuel consumption. Numerous studies have shown that the most promising direction of increasing dynamic characteristics and reducing fuel consumption are mechanical energy recovery devices that accumulate the energy of the rotating masses of the car during braking and transfer it to the same rotating masses at the moment the car starts moving. Analysis of the movement of light trucks using a mechanical energy recovery device can reveal changes in the dynamics of light trucks and fuel consumption.
 Purpose. Investigation of changes in dynamic characteristics and fuel consumption of a low-tonnage truck with a mechanical energy recovery unit using a model in the MATLAB Simulink environment.
 Methodology. Methods of mathematical modeling and analysis were used in the article.
 Results. The parameters showing the efficiency of operation of a low-tonnage truck with a mechanical energy recovery unit are obtained.
 Practical implications. The results obtained can be applied when designing a car to identify the optimal parameters of the vehicle’s power plant, which are used together with mechanical energy recovery devices.

Mechanical energy fluctuation in lower limbs during walking in participants with and without total hip replacement.

Mechanical energy fluctuation of the segments of lower limbs during walking has not been fully investigated. It was hypothesized that the segments may work as a pendulum, i.e. the kinetic and potential energies exchanged out of phase. This study aimed to investigate energy changes and recovery during gait in hip replacement patients. The gait data for 12 participants with total hip replacement and 12 age-matched control was compared. The kinetic, potential and rotative energies for whole lower limb and thigh, calf and foot, were calculated. The effectiveness of a pendulum effect was analysed. Gait parameters (speeds and cadence) were calculated. The results showed that the thigh had significant effectiveness as a pendulum during gait with energy recovery coefficient of approximately 40% while the calf and foot were less like a pendulum during gait. In comparison, energy recoveries of lower limbs in the two groups were not significantly different. If the pelvis was considered as an approximate to the centre of mass, however, the control group had a higher energy recovery than total-hip-replacement group by roughly 10%. This study concluded that, unlike centre of mass energy recovery, the mechanical energy recovery mechanism in the lower limbs during walking is not affected after total hip replacement.

Life cycle assessment (LCA) on waste management options for derelict fishing gear

PurposeDerelict fishing gear (DFG) is one of the most abundant and harmful types of marine litter that gets increasingly retrieved from the ocean. However, for this novel waste stream recycling and recovery pathways are not yet commonly established. To identify the most suitable waste management system, this study assesses the potential environmental impacts of DFG waste treatment options in Europe.MethodsThis study applies an attributional life cycle assessment (LCA) to four DFG waste treatment scenarios, namely a mechanical recycling, syngas production, energy recovery and landfill disposal. The scope spans from the retrieval and transport processes to pre- and end-treatment steps until the outputs are sent to landfill or assumed to substitute products or energy. Primary data was collected from retrieval and waste treatment trials in Europe. Contribution, sensitivity and uncertainty analyses were conducted using the LCA software SimaPro and ReCiPe as the impact methodology.Results and discussionThe results show that the mechanical recycling and energy recovery achieve the lowest potential environmental impacts. The syngas production and landfill disposal scenario are not environmentally competitive because they require too much electricity, or their avoided production credits were too small to offset their emissions. Unlike the pre-treatment and transport processes, the retrieval and end-treatment processes have a significant impact on the overall results. The transport distances, energy mix and market and technological assumptions are least sensitive, while changes to the waste composition significantly affect the results. Especially a reduced lead content benefits the human toxicity impact potential of the landfill disposal scenario. The uncertainty analysis showed that the results are very robust in nine of twelve impact categories.ConclusionsThis is the first LCA study that compares waste treatment options for marine litter. The results indicate that a disposal of DFG is hazardous and should be replaced with mechanical recycling or energy recovery. While this may be technologically possible and environmentally beneficial, economic and social factors should also be considered before a final decision is made. To further reduce environmental impacts, marine litter prevention should play a more important role.Graphical abstract

Agricultural Plastic Waste Management

This article aims at describing both the studies and results implemented in the framework of the H2020-EU research project “RECOVER: New bio-recycling routes for food packaging and agricultural plastic waste” which deals with the sustainability of innovative biodegradation processes for plastic waste and production, in any environmental, social, economic and safety matters. In such a framework, the POLOG University Centre (Livorno, Italy), reconstructed and analyzed the actual farm plastic waste supply chain, as described in the following sections. The first section is introductive and it has been intended as a primer to the most common different types of plastic materials. The second section has deserved to be a state of the art on the most relevant issues raised in plastic waste management. The third section deals with suitable approaches to address the environmental side effects of rapidly growing plastics production, use, and disposal. Some of these approaches were listed, such as physical treatment of the polymeric components, plastic reduction use and employment as much as mechanical and/or chemical recycling and energy recovery. The fourth section shows how some of the above main issues, which raise coping with plastic reduction and recycling, are suited to be coped with from a logistics perspective. Such logistics belong to the basic needs due to tackling any plastic waste supply chain, i.e. collection and transport to intermediate stock and final delivery to recycling plants and/or brownfields, applying the set of methodologies and techniques drawn from the well-known field of pick-up-and-delivery models. These last tasks become crucial when the main effort has addressed the enforcement of any feasible changes from the use of items made in old high environmental intrusive to their replacement with new agricultural and biodegradable plastics. The paper goes to end presenting shortly of a few suitable solutions that could be proposed and applied to the entire plastic waste supply chain. Finally, some concrete aspects of each phase of the supply chain were discussed and it was highlighted how much each of these can be best used in addressing the problem known throughout the world as the problem of the emergency of old plastic waste.

Rocker-profile design shoes improve pendular energy recovery in walking with no effects on total mechanical work

Rocker-profile design shoes are commonly used in clinical settings. Such footwear reduces in-shoe pressure over the forefoot area during the gait, and depending on the rocker-profile type (i.e., toe-only, heel negative, or double rocker), affects lower limb kinematics, kinetics, and muscle electromyographic activity. However, whether wearing rocker-profile shoes influence the dynamics of the body centre of mass (BCoM) is unknown. We used a mathematical procedure combining Lissajous contours and Fourier analysis to describe the 3D trajectory of the BCoM in walking with rocker-profile (RollingSole) and flat (Control) shoes at 0.97, 1.25, and 1.53 m s−1 in 30 participants. Harmonics amplitude and phase were compared using linear and circular statistics, respectively. External (Wext), kinematic internal (Wint,k) and total (Wtot) mechanical works, and the mechanical energy fraction recovered from a pendular exchange of potential and kinetic energy were also calculated. RollingSole shoes yielded greater Wext (1–9 %; P < 0.05) and fractional pendular energy exchange (1–8 %; P < 0.01), with lower Wint,k (2–5 %; P < 0.05) and unchanged Wtot (P ≥ 0.30). RollingSole shoes led also to a greater mean height of the BCoM (1–3 %; P < 0.01), and amplitude of the anteroposterior and vertical symmetric, and mediolateral 2nd-to-5th harmonics (1–30 %; P < 0.01). No differences between shoes were found for the harmonics phase (P ≥ 0.14). Our results indicate that RollingSole shoes enhanced an inverted pendulum-like behaviour of the BCoM during walking with no alterations in total mechanical work. This may result from the combination of rocker-profile design and greater BCoM height (through thicker soles) with such shoes, increasing recovery of mechanical energy in step-to-step transitions and mid-stance.

Thermodynamic analysis of an epitrochoidal rotary reactor for solar hydrogen production via a water-splitting thermochemical cycle using nonstoichiometric ceria

An epitrochoidal rotary reactor for solar hydrogen production via a water-splitting thermochemical cycle using nonstoichiometric ceria is proposed. The reactor performs solid-phase heat recovery in the form of mechanical energy via isentropic compression and expansion of the sweep gas. A thermodynamic analysis for a system consisting of the epitrochoidal rotary reactor and two exchangers is presented. Under typical conditions with a solar concentration ratio of 3000, reduction temperature of 1773K, oxidation temperature of 1073K, gas-phase heat recovery effectiveness of 0.9, mechanical energy recovery effectiveness of 0.85, and the ratio of the molar flow rates of sweep gas and ceria of 10, the solar-to-fuel efficiency is 13.2%. The thermodynamic analysis demonstrates the potential of using an epitrochoidal rotary reactor for convenient solid-phase heat recovery without sacrificing the solar-to-fuel efficiency.

Design of an Underactuated Powered Ankle and Toe Prosthesis.

Powered ankle/foot prostheses aim to replicate the biomechanical function of the missing biological limb. Biomechanical analysis shows that while the ankle injects positive energy into the gait cycle, the toe joint dissipates energy. Yet virtually all powered ankle/foot prostheses use custom ankle actuators in combination with carbon fiber foot springs to imitate the function of the missing ankle/foot complex. Here we introduce a powered ankle and toe prosthesis with an underactuated mechanism. The underactuated mechanism connects the toe and ankle joints, providing biomechanically accurate torque and enabling mechanical energy recovery during gait. The proposed powered ankle/toe prothesis is the first device to match the weight, size, and build height of microprocessor-controlled prostheses.

Flywheel-Based Boom Energy Recovery System for Hydraulic Excavators with Load Sensing System

A hydraulic excavator (HE) is a typical piece of construction equipment and is widely used in various construction fields. However, the poor energy efficiency of HEs results in serious energy waste and has aroused the attention of researchers. Furthermore, rising fuel prices and increasing stringent waste gas emission legislation sparked demand for ways to improve energy efficiency. Recovering the otherwise wasted boom potential energy of a conventional HE by proper methods offers the potential to improve the fuel efficiency of HEs. In this paper, a mechanical energy recovery system consisting of a pump/motor and a flywheel is presented for HEs using a load sensing system. When the boom moves down, the boom potential energy is converted into mechanical energy by the boom cylinder and the pump/motor to accelerate the flywheel. When needed, the captured energy stored in the flywheel is converted back into a form of pressure energy to directly drive the boom cylinder up without throttling the main valve. In the lifting process, a compound circuit that consists of a throttling control circuit and a displacement control circuit is presented. A control strategy is proposed to optimize the energy recovery and reuse procedure. A 4-t HE is used as a study case to investigate the energy-saving potential of the proposed system. Numeric simulations show that the proposed system, when compared with a conventional load sensing system, can reduce as much as 48.9% energy consumption in a non-loaded cycle of boom lifting and lowering process. As to a fully loaded case, the energy-saving rate is 16.9%. This research indicates the flywheel-based scheme is promising for developing an energy-efficient fluid power system for HEs and reducing energy consumptions.

Model based control of the inlet pressure of a sliding vane rotary expander operating in an ORC-based power unit

• Experimental analysis on Sliding Vane Rotary Expander in ORC plant. • Development of a new approach for volumetric losses calculation. • Inlet pressure control strategy based on expander speed variation. • Effectiveness assessment of the proposed control strategy. • Performance optimization through the proposed regulation strategy. Sliding vane rotary expanders (SVREs) are widely used in organic Rankine cycle (ORC)-based power units for low-grade heat recovery because of their capability to deal with severe off-design working conditions. In particular, the speed of SVREs is a very effective operating parameter, together with the speed of the pump, to regulate the recovery unit and to lead the involved components in an acceptable operating behaviour when they are far from the design conditions. In this study, a control strategy based on the variation in revolution speed of a SVRE was developed, where the inlet pressure of the expander is the main controlled property, which must be verified when the flow rate of the working fluid is changed to match the thermal power recovery at the hot source. In fact, pressure level control is a key point of the recovery unit for thermodynamic reasons and for the safety and reliability of the expander and, more generally, of the whole recovery unit. The proposed control strategy is based on an original theoretical procedure that relates the expander speed, inlet pressure, volumetric efficiency, and working fluid mass flow rate in an analytical form. This analytical formulation is widely nonlinear and is simplified for use as a tool for the model-based control of the inlet expander pressure. An experimental activity performed on a SVRE operating in an ORC-based power unit, fed by the exhaust gases of a supercharged diesel engine, was the base of the analytical formulation. This provided the possibility of deriving a simplified model-based control of the expander inlet pressure and assessing its effectiveness and limits during off-design conditions. Higher expander global efficiencies were obtained (up to 45%), allowing a greater mechanical energy recovery (up to 2 kW).