Development research of reflection-absorption compound type fluid pulsation attenuator
Based on the disadvantages analysis of the existing fluid pulsation attenuator, two reflection-absorption compound type of fluid pulsation attenuators which are both composed of a chamber and a mass-spring-damping system are developed: in-line reflection-absorption compound type of fluid pulsation attenuators (in-line RAFPA) and side-branch reflection-absorption compound type of fluid pulsation attenuators (side-branch RAFPA). The transfer matrix models of the two attenuators are established as well as expansion chamber attenuator and Helmholtz resonator. Based on the transfer matrix model, the transmission loss of the four attenuators is given out to evaluate their attenuation characteristic. The attenuation characteristic comparisons of in-line RAFPA with expansion chamber attenuator and side-branch RAFPA with Helmholtz resonator are carried out respectively. And the effect of the mass-spring-damping system to in-line RAFPA and side-branch RAFPA is investigated. The simulation reveals the two reflection-absorption compound type of fluid pulsation attenuators have better attenuation characteristic and are more compact than expansion chamber attenuator and Helmholtz resonator.
Numerical study on a compound hydraulic pulsation attenuator based on string-fluid resonance
In designing a hydraulic pulsation attenuator (HPA), the size and effective frequency band are two factors needing to be compromised. To improve the performance of HPA under a given volume, this paper proposes a compound HPA (CHPA), which works by string-fluid resonance and attenuation of the expansion chamber. The numerical model of the CHPA is derived using the method of electric-hydraulic analogy and evaluated by simulation and experiments. The experiment results show that the average relative error of the frequency position is within 5 Hz. Finally, a numerical comparison study is demonstrated, indicating that the attenuation strength of the CHPA at given periodic pulsation frequency is higher than ECA, SBHR, STPA and BCA by 82.3 %, 71.2 %, 257.1 % and 65.1 %, respectively.
Heat Recovery Systems
Geothermal energy is recovered from an underground zone of relatively hot strata via a borehole into which is inserted a heat pipe system containing a working fluid, the heat pipe system comprising an assembly of two tubes in concentric relation, the inner tube being constituted by a relatively small diameter capillary for the return of working fluid to the vicinity of the zone of the relatively hot strata. The working fluid is preferably assisted in its return under gravity by means of a pump. The system includes heat exchange means operable to recover thermal energy from the working fluid. A third and outermost tube may be used to reduce heat losses, this third tube enclosing the two tubes over all but that part of their length which is in the zone of relatively hot strata.