Thermo Definition and 299 Threads

Homework Statement Find the equation of state given that k = aT^(3) / P^2 (compressibility) and B = bT^(2) / P (expansivity) and the ratio, a/b? Homework Equations B = 1/v (DV /DT)Pressure constant ; k = -1/v (DV /DP)Temperature constant D= Partial derivative dV = BVdT -kVdP (1) ANSWER is...

Homework Statement [/B] I've attached a screenshot of the problem, which will probably provide much better context than my retelling. I'm having problems with parts f and g. The most relevant piece of information is: "To get used to the process of Taylor expansions in two variables, first we...

Homework Statement Rather than retyping the problem, I've uploaded a screenshot here >> http://imgur.com/EB5MrtP Homework Equations Q_1 + Q_2 + Q_3 ... = 0 mc \Delta T = Q The Attempt at a Solution a. Q_{tea} + Q_{met} + Q_{cr} = 0 I converted the temperatures to K, so T_{cr} and T_{met} =...

Homework Statement Case, P[bar], T[C], v[m3/kg], u[kJ/kg], x[quality], State a) 1.5, ?, ?, 3000, ?, ? b) ?, 120, .6, ?, ?, ? c) 3, ?, ?, 2543.6, ?, ? d) ?, 190, ?, ?, 20%, ? e) 25, 100, ?, ?, ?, ? f) ?, 240, ?, ?, 0, ? Homework Equations We are supposed to use the steam tables in the back of...

On page 200 in the 7th edition of Intro to ChemE Thermodynamics by Smith, Van Ness, and Abbott, there is an equation that has always bugged me since reading it (or rather the interpretation of it, not the derivation). It is equation 6.1 and states: d(nU) = T d(nS) - P d(nV) with n = moles in the...

Good day , could someone please point me to a device that would have say two wire terminals and could interrupt the flow of current between them when a dangerous temperature is reached? the idea is simple , I built a lamp and I need some failsafe mechanism that would turn the lamp off when it...

Homework Statement [/B] Thermodynamics problem Air enters a compressor at a temperature of 290 Kelvin and pressure 100 kPa with a stable volume flow of 2.5 m^3/s. The output temperature of the compressor is is 400 Kelvin and the velocity of the flow is 30 m/s. Air is implied to be an ideal gas...

This is for work. I need to make a table for a client. What we did: had two different closed systems, only difference is material. We had frozen goods in both containers, the containers were both removed from the cooled surroundings they were in and placed outside. The temperatures were...

In a thermo flask the air between the outer and under wall is sucked out and a vacuum is created. So the air pressure should push the outer wall towards the inner wall and vice versa. But it doesn't happen. Why?

This question has been bugging me for long. Specifically I'm wondering about it in the context of Pressure-Tempreature phase diagrams. With these diagrams you can deduce stuff like the Clausius-Clapeyron equation and stuff like that. But certain things confuse me, e.g.: There is this mental...

The General Energy balance equation is: ∑ENin - ∑ENout + Egen = Est (in rate form - don't know how to put the dot above) I know that Est is 0 when the system operates at Steady State Steady Flow (SSSF). I have 2 formulas for ΔE in "Q-W = ΔE" 1) ΔE = ΔU + ΔKE + ΔPE 2) ΔE = m[h2 - h1...

Hi all, I have another thermo q I am stuck on. You can see the question and my attempted answer below. Part 1 is fine, Part 2 i don't know where to start, and part 3 I thought was correct however the answer is wrong! I think I am doing something wrong with the U2 part of internal energy, just...

Stuck on part of this question regarding Cv value: I don't understand how one can get the value for Cv, I tried saying Cp - Cv = R (1) Cp/Cv = 1.5.so rearrange gives Cp=1.5Cv (2) Now sub 2 into 1 and that gives 0.5Cv = R But according to solutions that's wrong, Cv is 1010 and I can't get...

While reading some articles on Wikipedia I came upon one interesting statement that essential says (I've rephrased for clarity; correct me if I'm wrong): "The Time-asymmetry of the second law of thermodynamics is due to the initial conditions of our universe" Can someone elaborate on what...

Homework Statement The last part of my question reads: Give the equations you would use to determine reactor thermal output if the plant is to produce 1000 MWe. All expressions for work and heat transfer rate should be expressed in terms of the appropriate mass flow rate ratios. Homework...

Homework Statement The filament is 30 cm long and has a diameter of 1.5mm. The filament is drawing 15 watts and has an emissivitity of 0.9. The surroundings are at 283 k. Estimate the surface temp of the filament in K. Homework Equations N = Wcycle/Qin, W cycle = Qhot - Q cold. The Attempt at...

I am currently working on a prototype for a new product. Whithout exposing the product to much it is simply put a cooling box run by solar panels with a battery backup. Due to the fact that the surface area available for solar panels is limited the cooling module needs to be quite small and...

Homework Statement When lead is melted at atmospheric pressure, the melting point is 600K, the density decreases from 1.101x104 to 1.065x104 kgm-3. The latent heat is 24.5 kJ kg-1 Estimate the melting point of lead at a pressure of 100 atm. Homework Equations I haven't been able to find any...

Homework Statement Given T=572 ºF, pressure= 145 psi (g) using the steam tables and ideal gas law Molar Mass= 18 g/mol for water Find: Is the water vapour acting ideally? Homework Equations Ideal Gas Law: PV=nRT P is the pressure =145 psi (g) V is the molar volume n= mol R= Ideal gas constant...

1. Homework Statement Given the rate of pipe= 100 kg/s The steam flow has quality x= 80% = 0.8, pressure= 90 atm Find the volumetric flows of dry steam and liquid water 2. Relevant equations...

< Moderator Note -- Thread moved here to Homework Help forum > One volume of CH4 is mixed with V volumes of air (78 vol.% N2,21 vol.% O2,1 vol.% Ar) at 1 atm and 25°C; then the mixture is ignited. Find the temperature of adiabatic combustion (the adiabatic flame temperature). The volume of air...

Homework Statement A liter of air, initially at room temperature and atmospheric pressure, is heated at constant pressure until it doubles in volume. Calculate the increase in its entropy during this process. so Ti= 300K, Volume which is 2Vi=Vf; Pressure is constant Homework Equations ΔS...

Hi have some thermal physics question would like to clarify. Thanks :) Question 1: For a substance in a pure phase heated at constant pressure, the heat absorbed is related to ____________ (a)the molar heat capacity of the substance (b)the amount of substance (c)the change in the kinetic energy...

Homework Statement Gaseous helium is contained in a rigid container with a volume of V=0.5 m3, and is initially at a pressure of 500 kPa. Agitation by a stirrer transfers 250 kJ of work to the gas in an adiabatic process. Cv for the gas is constant and equal to 12.46 kJ/kmol*K. What is the...

Homework Statement R134a rests in a compressed fluid can at 120psia, and a specific volume of 0.38ft3/lbm. What is its temperature and quality? Half of the mass is now vented off to the atmosphere. The can is allowed to exchange heat with the surroundings at 100°F until they are in thermal...

The best laboratory vacuum has a pressure of about 1.00 x 10-18 atm, or 1.01 x 10-13 Pa. How many gas molecules are there per cubic centimeter in such a vacuum at 293K? PV = nkT P/kT = n/V = N (# of molecules per cm^3) Since V is typically in units of m^3 or liters, should I make my...

I have read quite a few discussions about this topic of entropy and if this universe has a truly closed or, as I prefer to describe it "undisturbed", system and I have read some discussions about a freezer and chilling ice cubes etc. etc... To my extent of reading these conversations no one has...

Please help me qualitatively in the following points : 1) If in a system(consider a cylinder) fixed with a piston , if the piston is moved suddenly then how can a process be adiabatic. 2) I understood that the process would be irreversible but, if the process is adiabatic then is the relation...

Hi - I am currently working on a paper verifying some thermal hydraulic code against experimental test data for subcooled water subchannel flow. I have close to 1000 points in excel all listed with T & P and the process for inputting the corresponding enthalpies for subcooled water by lookup...

Homework Statement An insulated nozzle receives are at a negligible velocity at a pressure of 150kpa and temp of 25 degrees C. if the flow passing through the nozzle expands to 100kpa in an isentropic process, calculate the temperature and velocity of the air leaving the nozzle.The Attempt at a...

..Quick rundown on 0-th principle of thermodynamics in relation to GR and QM. Some insight on LQC-(slide to 19:07) using quantum state 'of' time in a semi-classical approximation. Fun way to think of things.^^

I work at a company that manufactures TPU screen filters for the mining industry. I've got a test to do to inspect whether the qaulity of the TPU is affected by time in the heated barrel of the injection moulding machine. The TPU material sits in the barrel due to tea and lunch breaks (15 - 30...

Hello, I`m a bit confused about PV work. Here is the situation I am facing. δw = P dV and dw = F dx δw is an inexact differential, because it's path dependent. I read some articles that equal δw with dw. saying that P dV = F dx For what path is that True? In other words...

Homework Statement Basically I just want to know why if I increase the pressure from 0 to 10MPa in a isothermal system containing oxygen, the enthalpy will decrease? Homework Equations Delta H = Delta U + delta PV PV = nRT PV = ZRT The Attempt at a Solution During a...

1. Unit mass of a fluid at a pressure of 3 bar, and with a specific volume of 0.18 m3/kg, contained in a cylinder behind a piston expands reversibly to a pressure of 0.6 bar according to the law p = c/v2, where c is a constant. Calculate the work done during the process. 2. P1V1=P2V2 3. I know...

I'm pondering courses for the autumn and I'm at a bit of a crossroad. Doing an intro thermodynamics class right now which involves all the stuff I don't really enjoy - measurements, looking stuff up in tables, memorization, etc. Very non-theoretical. It feels like an AP chemistry class...

Also sorry if you feel this is in the wrong place. I was unsure where to put it. I was wondering what the main differences in content/way problems are solved in Mechanical Engineering Thermodynamics, Chemical Engineering Thermodynamics, Thermodynamics of Materials ( for MSE), Thermal Physics...

if thermo couple ammeter full scale deflection is 10 Amp, for 1/5 th scale what is the Reading?

Hello all, I'm choosing my classes for spring semester and am unsure about which of these two classes I should pick (topic title). My major is electrical engineering and I want to hopefully go to graduate school at my current school for their micro-systems nano-systems program listed here (...

Homework Statement The problem provides two paths. P1,V1,T1------->P1,V2,T3 (this is the only one i do not understand) for AN IDEAL GAS reversible expansion Pressure---constant Volume---not constant Temperature---not constant Calculate the q(rev)=? work(rev)=? and ΔU=? Homework...

I have a homework problem that I completed but I am not sure if it is correct. I was wondering if you guys could let me know if my thought process is correct of if I need to modify my solution. The problem is: An adiabatic and rigid open vessel contains 4 kg of air at 300 K and has a volume...

Hi The thermo problem is as follow: I have a fireplace and I have an underfloor water pipe heating. currently the underfloor water is heated by gas burner. I want that the water will also be heated by the fireplace, so I plane to place a chopper pipe inside the fireplace and run the...

Dear PF, I am hoping you can help. I am trying to test the the speed that a beetle heats up under standardized conditions. I have buried a small container in crushed ice and place a beetle and thermometer inside. I wait until the thermometer and has reached 0°C, the idea then is to increase...

So one can even have "beyond standard Thermodynamics" :biggrin: I just came across this and it seems interesting. http://arxiv.org/abs/1207.0434 Laws of thermodynamics beyond the von Neumann regime Dario Egloff, Oscar C. O. Dahlsten, Renato Renner, Vlatko Vedral (Submitted on 2 Jul 2012)...

1 kg of steam at a pressure of 10 bar and temperature of 400°C is contained in a cylinder closed by a piston. The steam is compressed by the inward motion of the piston until the pressure is 50 bar. The work done on the steam is 250 kJ and the heat transfer from the steam is 700 kJ. Calculate...

Im trying to understand this concept of deriving an expression for (\frac{\partial T}{\partial P})s in terms of T, V, Cp, \alpha, and \kappaT (\frac{\partial T}{\partial P})s is evaluated by measuring the temperature change and the specific volume change accompanying a small pressure change...

Homework Statement A power plant generates 1300MW and operates at 315 °C a 20°C heat sink is available. what is the minimum rate at which heat must be discarded? Homework Equations not really sure how to begin this one, have a feeling it is related to dq=Tds at constant pressure giving...

Homework Statement in a cylinder, 1.2 mol of an ideal gas, gamma = 1.67 initially at 3.60 x10^5 pa and 300k, is compressed until the volume is halved. I need help with 1) c and 2) Compute work done on the gas if the compression is: 1) a) isothermal b) adiabatic c) isobaric...

one mole of liquid water (100 deg C, vapor pressure = 1 atm) in a container is introduced into an evacuated vessel maintained at 100 deg C and allowed to evaporated. The volume of the vessel is such that the final pressure of the gaseous water is 0.1 atm. Given the (normal) latent heat of 9,730...

Thermo Question! Homework Statement CCl3F and CCl2F2 have been linked to ozone depletion in Antarctica. As of 1994, these gases were found in quantities of 261 and 509 parts per trillion (1012) by volume (World Resources Institute, World resources 1996–97). Compute the molar concentration...