This project is about another particular application of a particular embodiment of the patent: A Long Stroke Steam Engine using Solar Generated Steam. The machine elements such as springs, shafts, bearings, chains and belts comprising this embodiment will require design to withstand fatigue failure due to cyclic loading as the reciprocator operates at relatively high speed.
You Are Required To Perform Design Calculations As Outlined Below
Data setting out the design requirements for the Long Stroke Steam Engine are provided in the Excel file entitled Project_LS_OilWell_Pump.
The bending effects of these high inertial forces on the stub shafts may be minimized by positioning compression springs at the end regions of the carriage movement. These springs may be designed to assist in the deceleration of the carriage while the special chain link travels around the sprocket.
It is expected that the engine will be required to operate at frequencies up to 50 cycles per minute and that this will cause high inertial forces bearing on the two stub shafts protruding from the special chain link which hauls the carriage. The sudden pressure increase as valves close during the pumping action will cause fluctuating loads on all components of the system including both pressure induced stress and tensile stress on the down-hole pump elements.
Stage 1 - Refer to the AREVA file about the AREVA Solar Thermal Power Plant:
Assume that the system that you design is to produce 100 kW-hrs of electrical energy per day at a location having clear sunny days such as many Australian farming places.
Taking into account that the proposed steam engine net efficiency will be as low as about 5% whilst the generator efficiency is likely to be no more than 85% estimate the area of solar mirrors required. Be generous!
Based on the above power rate and making a reasonable estimate of friction loss determine the power requirement for the machine. Also determine the peak piston force and the average piston force during the cycles. Note that the pumping action will cause fluctuating load on the chain.
Size the electrical generator required and a key coupling to the sprocket shaft. For this purpose size that the sprocket shaft diameter.
Stage 2 - Design of cantilever shaft and selection of deep groove ball or tapered roller bearings:
Design the cantilever shaft (and select suitable bearings to carry this shaft) for the drive sprocket. Select silent chain for this machine. Details of the arrangement for this shaft are given in the Excel spreadsheet 5. Assume that the generator requires speed reduction by means of a toothed belt pulley system to be driven by this shaft. The belt tension will place a load on the end of the shaft. Assume a belt tension when designing the shaft.
Stage 3 - Design and give full specifications for a compression spring arrangement at each end of the carriage motion to assist in its deceleration and re-acceleration:
Design suitable springs to minimize the inertial loads on the stub shafts of the special hauling link. The springs are to buffer against the carriage as it approaches each end of its travel with a suitable buffering component.
Stage 4:
Check out the suitability of your selected chain for this application and size the stub shafts on the special hauling link. Details of this link are included in the Excel spreadsheet 4 and in the patent document.
Stage 5:
Design the pulley drive having a suitable reduction ratio from the generator to the drive shaft. Assume that the generator rotational speed is 1500 rpm. Submit a report discussing each aspect, all assumptions and include all references.