A Smart Energy Recovery System to Avoid Preheating in Gas Grid Pressure Reduction Stations

Preheating is often required to prevent hydrate formation during the pressure reduction process in a natural gas distribution network’s pressure reduction station. This paper examines an energy recovery method to avoid the cost and energy consumption of this preheating. The primary aim is to assess the techno-economic feasibility of an energy recovery system based on the Ranque–Hilsch vortex tube coupled to a heat exchanger for large-scale application to the gas grid. To this end, a techno-economic model of the entire energy recovery system was included in an optimisation procedure. The resulting design minimises the payback period (PP) when the system is applied to the pressure reduction stations belonging to a particular gas grid. The pressure reduction stations always operate at an outlet pressure above atmospheric pressure. However, available performance models for the Ranque–Hilsch vortex tube do not permit prediction at backpressure operation. Therefore, a novel empirical model of the device is proposed, and a cost function derived from several manufacturer quotations is introduced for the first time, to evaluate the price of the Ranque–Hilsch vortex tubes. Finally, a nearly complete set of pressure reduction stations belonging to the Italian natural gas grid was chosen as a case study using actual operating parameters collected by each station’s grid manager. The results indicate that the environmental temperature strongly affects the technical and economic feasibility of the proposed energy recovery system. In general, pressure reduction stations operating at an ambient temperature above 0 °C are economically desirable candidates. In addition, the higher the energy recovery system convenience, the higher the flow rate and pressure drop managed by the station. In the Italian case study, 95% of preheating costs could be eliminated with a PP of fewer than 20 years. A 40% preheating cost saving is still possible if the maximum PP is limited to 10 years, and a small but non-negligible 3% of preheating costs could be eliminated with a PP of fewer than 4.5 years.

Performance Assessment of Thermoelectric Generators with Application on Aerodynamic Heat Recovery

Based on thermoelectric generators (TEGs), an aerodynamic heat energy recovery system for vehicle is proposed. A mathematical model describing the energy conversion law of the system is established, and the integrated calculation method which combined aerodynamic heating and thermoelectric (TE) conversion is given. Furthermore, the influences of the typical flight Mach number, flight altitudes and the length of TE legs on the energy conversion behavior of energy recovery systems are investigated. The performance of the energy recovery system is analyzed and evaluated. The results show that, the decrease of flight altitude and the increase of Mach number will obviously improve the performance of the heat energy recovery system with TEGs. The increase of leg length will increase the temperature of the hot end of TEGs and reduce the heat absorbed at the hot end. When the external load, Mach number and flight altitude is fixed, there exists an optimal length of legs corresponding to the maximum output power and maximum conversion efficiency of the system. The results will have significant positive impact on thermal protection and management of supersonic / hypersonic vehicles.

Organic Rankine Cycle for Energy Recovery System

This book contains the successful invited submissions [...]

Bacteria Energy Recovery System Using Natural Soil Bacteria in Microbial Fuel Cells

This paper describes a two-cycle bacteria energy recovery system (BERS) to power two embedded sensors: an ultra-low portable pH sensor and a sound sensor. The designed unit can handle up to seven microbial fuel cells (MFCs) to charge a super-capacitor. This allows the BERS to provide a constant 0.14 mW without further electrical components for signal conditioning. The two cycles were driven with a 100 kΩ load and a 10 Hz frequency. The BERS is also self-powered with an integrated start-up unit to be self-activated when the MFCs charge the energy-storing unit after three days. The BERS powered pH sensor has an error below 5% at 25 ∘C and is able to work continuously while being activated for 4 h. The performances of the pH and sound sensors were determined based on a compromise between accuracy and power consumption.

IMPROVEMENT OF THE ENERGY RECOVERY SYSTEM OF A TIMBER TRACTOR WITH A LUMBER TRUCK

The place of road transport in logging production has been considered. The main advantages of using timber tractors with timber drags in comparison with other layout schemes of timber road trains have been described. Conse-quences of dynamic loads acting on the pivot of the turning bunk of a timber-carrying area from frequent braking of a timber tractor with a timber drag have been given. Based on the analysis of scientific works of foreign scientists, the promising direction of research in the field of recuperation of various types of energy in road transport is substantiated, which makes it possible to reduce dynamic loads during braking in the pivot pin and at the same time accumulate, with subsequent useful use, energy unproductively dissipated into the surrounding space from the energy forces of the trailer with a pack of whips. The design of the main manufacturers of platforms for timber haulers with timber drags has been described. The requirements for timber haulers with timber drags operated on public roads have been considered. The main forces acting on the links of a timber tractor with a timber drag during braking have been analyzed. Diagrams of the mutual positions of a timber tractor with a timber drag when moving along a timber road on the rise, downhill and turn have been given. The analysis of the dependences of the forces arising in the pivot of the swivel bunk of a timber platform during the movement of a timber tractor with a timber drag on the turning radius and speed of movement has been carried out. A promising design of a recuperative bolster device for a timber haulage site has been proposed. It enables to accumulate hydraulic energy during frequent braking of a timber tractor with a timber drag, followed by its use in the process of loading and unloading timber by a hydraulic manipulator