Mechanical Engineering Answers

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If the volume of the room is 15 m3, what ventilation rate in ACH must be maintained to keep radon levels below the US EPA recommended limit of 4 pCi/liter? What is the primary sink for radon in the cellar?

A root cellar receives an input of 0.1µCi of radon-222 per hour through the dirt floor. Radon-222 has an approximate half-life of 3.8 days.

Calculate Machine Cutting Time (show all work) A person cuts a piece of Bronze that is 4" long with a 2" Dia., down to 1.600 Dia. It is done in 3 passes. (2 roughing and 1 finishing pass) Length Time = Rate Rpm Length = Length of cut Rate = Feed x Rpm CS x 4 D Pass 3 = 1.610 to 1.600 dia. Pass 1 = 2" to 1.800 dia. Pass 2 = 1.800 to 1.610 dia. CS = 90 for roughing and 100 for finishing. Feed = .015 - .025 roughing and .003 - .010 finishing Length = 4" What is the machine cutting time in seconds)?

One kiliogram of steam expands isentropically from 2.0 MPa and 360°C to 90°C. find the final quality and the work for non-flow and steady flow process.

A reheat-regenerative engine receives steam at 207 bar and 59.3 °C, expanding it to 38.6 bar, 343°C. At this point the steam passes through a reheater and reenters the turbine at 34.5 bar. 593°C, hence expands to 9 bar, 492°C, at which point the steam is bled for feedwater heating. Exhaust occurs at 0.07 bar. Beginning at the throttle (point 1) enthalpies are known (in kJ/kg). 

An ideal reheat turbine with one-stage of reheat receives steam at 8.0 MPa, 480 °C. Reheat pressure is 0.83 MPa and exhaust pressure is 0.007 MPa. The work is 1559 kJ/kg and the thermal efficiency is 41.05%. Find the temperature of the steam leaving the reheater. 

Expand 2 kg of steam at 15 bar, 320°C, into the wet region to 100°C in a polytropic process where pv^1.21 = C. Determine (a) y2, (b) ΔH, (c) ΔS, (d) nonflow and steady flow work, and (e) Q.