Design head will be selected according to the task. Pressure hydraulics - the linear size, which depicts a specific fluid flow (fluid weight unit correlated) energy given point.

This 'pressure' is not usual pressure i think, I didnt translated maybe properly. Thank you guys to try solve this question. But yeah, come to think of it, isentropic efficiency can't be used with incompressible substances, so, disregard my above explanation.Дid they assume the outlet pressure at atmospheric or make some other kind of simplifying assumption? As SteamKing pointed out, without an inlet or exit pressure (and temperature or some other property to nail down the state), there really isn't enough information to solve that problem. Just not enough information to answer the question, so I made up the best solution I could that looked close to engineering equations I'm familiar with. Did he (asdarw) specify that the substance was compressible? Otherwise, if you can assume an incompressible fluid, which based on his lack of supplying any other information on the problem, I was forced to make some kind of assumption, that's what I got.Д«ut then again, I guess if it were an incompressible substance, it wouldn't be using an isentropic efficiency, which begs the question, is h an enthalpy? Quite small for an enthalpy. Without this information, you're just guessing.ДЇor a compressible substance, yes. You need to know the inlet conditions of the steam entering the turbine (pressure and temperature) and exit conditions (pressure and temperature) in order to calculate the amount of work extracted. The change in energy is not determined solely by the difference in pressure the temperature of the steam is also changing as it expands through the machine. Turbines operate by extracting energy from the expansion of steam through the device. Let's make sure I understand the variables first: That being said, there is enough to calculate the delta P (but not a static inlet or outlet pressure as you pointed out) without having all the other information. Good old thermo.ДЄs for the second question, I'm thinking that perhaps the pressure is a change in pressure, or what I always call the delta P. I would have done the problem 100% the same. Good job on the first question, SteamKing. What's this equation, where is it derived from? It's in the answers for a question, the question asked to calculate the work done by the air in a cylinder as it expands out.

The property info comes from the attached tables: The isentropic work (or more accurately, the power) is therefore W = m*(hi - ho) = 0.5 kg/s * (3423.1 - 2321.7) kJ/kg The enthalpy of this mixture can be calculated using the saturated liquid properties: S = 6.8826 kJ/kg*K = sf + x * sfg, where x is the quality of the vaporДoing the algebra and solving for x = 0.870, or a vapor quality of 87% Then h = 3423.1 kJ/kg and s = 6.8826 kJ/kg*KДЇor P = 30 kPa, we need to find the properties for s = 6.8826 kJ/kg*K, Since Mollier diagrams are hard to find on the web, you can also use steam tables. However, since you have specified a turbine operating isentropically, then using a Mollier diagram (a special diagram of enthalpy versus entropy), the state line of this turbine will be a single vertical line running from the inlet point down to the exhaust pressure of 30 kPa. Unless you know the enthalpy of the inlet and exhaust steam, yes, you need to refer to steam tables.ДЇor your exhaust condition, knowing the pressure is often not enough information. You can email an HTML report and spreadsheet attachment that includes all of the steam property inputs and results.Firstly, lets assume the expansion is isentropic.ДЇrom this, how do we find the power generated and final steam quality?Дo we look at steam tables, W = m(flow) (h_1 - h_2) - is that helpful? You can specify additional parameters such as the types of units to display, the maximum allowable input values, and more. This is perfect for students who often rely upon the more static printed steam tables in engineering text. Parameters and easily altering these inputs using the slider control. It allows you to view results by selecting a variety of input It is powered by the actual steam-table formulas, so you can calculate for all ranges of input values. This app is not just a steam-table lookup app. The Steam Tables app allows you to calculate for 23+ different combinations of input parameters including: This app is a universal app that works on both the iPhone and iPad and adjusts its screen size accordingly. The Steam Tables app is the #1 selling iOS app for quickly calculating saturated and superheated steam properties.

Steam table thermodynamics calculator