Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, radiation, and physical properties of matter. The behavior of these quantities is governed by the four laws of thermodynamics which convey a quantitative description using measurable macroscopic physical quantities, but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to a wide variety of topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering and mechanical engineering, but also in other complex fields such as meteorology.
Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Nicolas Léonard Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Scots-Irish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854 which stated, "Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency."
The initial application of thermodynamics to mechanical heat engines was quickly extended to the study of chemical compounds and chemical reactions. Chemical thermodynamics studies the nature of the role of entropy in the process of chemical reactions and has provided the bulk of expansion and knowledge of the field. Other formulations of thermodynamics emerged. Statistical thermodynamics, or statistical mechanics, concerns itself with statistical predictions of the collective motion of particles from their microscopic behavior. In 1909, Constantin Carathéodory presented a purely mathematical approach in an axiomatic formulation, a description often referred to as geometrical thermodynamics.
I am doing a project and this is a problem were are having:
We are trying to calibrate a MQ-3 sensor with an arduino uno board, however we have to do a hand calculation to arrive at the theoretical ethanol content (amount of ethanol saturated in the air) before we can calibrate the sensor...
I am try to calibrate an MQ-3 sensor with and Arduino board.
However, I need a little help with thermodynamics, I am using a container of alcohol which has a volume of 591.470 mL, only 100mL is filled with 100 proof (50%) alcohol. However I need to calibrate the sensor to the content of...
I read that entropy is a measure of disorder. Or in other words, unpredictability. So if I have a fair 50/50 coin. It is at maximum entropy (unpredictability). If I have a two headed coin I have zero entropy. It seems that the more possible unpredictable states, the higher the entropy.
Now...
A steam power plant operates on an ideal reheat–regenerative Rankine cycle with one reheater and two open feedwater heaters. Steam enters the high-pressure turbine at 10 MPa and 600°C and leaves the low-pressure turbine at 7.5 kPa. Steam is extracted from the turbine at 1.8 and 0.3 MPa, and it...
This is a very simple problem, though I have arrived at two different results and I would like some help to procceed (I'm not sure if this is the right section, though this is not a homework):
"2kg are confined in an adiabatic cilinder through a frictionless piston activated by an elastic...
Homework Statement
http://i754.photobucket.com/albums/xx183/reddiesel08/Q2.jpg
Homework Equations
e = 1 - (Tc/Th)
(Temp in Kelvins)
The Attempt at a Solution
e = 1 - (300k/520k) = .42 or 42%
No because the engine can only perform 42 J of work for each 100 J of energy.
Homework...
Urgent! Thermodynamic refrigerator
Homework Statement
One mole of a monatomic ideal gas is allowed to expand isothermally from an initial volume of 10 liters to a final volume of 15 liters, the temperature being maintained at 400K. The work delivered is used to drive a thermodynamic...
Hi Everyone, I have been researching for days, and am still very confused, so thought I might turn here for assistance.
I know the minimum free energy represents the state of maximum stability for a system. Free energy is decreased when enthalpy decreases and entropy increases. I understand...
Homework Statement
A thermodynamic engine is operated between two cooler bodies A and B, extracting work until the two cooler bodies reach a common temperature T_f. This work is then used as the input to a heat pump, extracting heat from the cooler pair and heating the hot body C. Find the...
Hey everyone,
I'm a bit confused with the meanings of f, g, and fg subscripts in the thermo steam tables (e.g. hf, hfg, hg). If there is saturated steam, part of the enthalpy is in liquid, hf, part is encapsulated in the vapour, hg, but what is hfg? Also h = hf + (x)hfg. h here is the total...
It is often said that phase transitions only exist in the thermodynamic limit based on some proof like:
-A system has time-reversal symmetry thus its TOTAL free energy F(H)=F(-H) (H is the field) therefore the magnetization is
M(H)=\frac{\partial F(H)}{\partial H}=\frac{\partial...
Homework Statement
1. Explain the term thermodynamic potential.
2. Explain the motivations for defining the enthalpy, the Helmholtz free energy and the Gibbs free energy.
3. The Helmholtz and the Gibbs free energy are measures of the distance to thermodynamic equilibrium. Explain...
Homework Statement
A 80 kg man is running and each second he needs a energy of 812.77 J. Find:
a) The speed (in m/S) of the runner.
b) How many kcal will be burn in one hour with the speed calculated in a)?
Homework Equations
Kinetic energy; kcal = 4184 J
The Attempt at a...
Homework Statement
1. In Air compressor cycles, the work done is calculated by integrating vdp and not pdv(like we'd do in otto cycle or any other thermodynamic cycle)...why?
2. In Rankine cycle. we calculate work done by making use of enthalpy calculations whereas in brayton cycle and...
Homework Statement
I was given and writing assignment which requires me to write a two-page report on how an organic matter like a potato can exist according to the Laws of Thermodynamics. I will be evaluated on how well I explain scientific principles and how accurate my statements are. The...
Well I've been doing fairly complex thermodynamics in classical mechanics lectures with a bit of medium to advanced class, first of all , it took me a very long time to wrap my head around the concept of Entropy, however I still don't understand why we use ln (Natural Log) to calculate the...
Homework Statement
A 70 ft3 rigid insulated tank contains air at 14.7 psia and 80 º F. The tank is connected to a supply line through a valve. Air is flowing in the supply line at 75 psia and 80 º F. The valve is opened, and air is allowed to enter the tank until the pressure in the tank...
Ok, I have an assignment to do in MATLAB involving the following problem, I am having a problem with my results, I believe I have coded everything correctly with the parameters of the problem yet as my plots show, there is an error in my calculations, any suggestions? I am attaching my problem...
Today, during class, our professor went through a simple example about Piezoelectricity. We have a cylinder with a trapped ideal gas and a piston which is part of a capacitor together with the bottom of the cylinder. The voltage across the capacitor is \Phi, and the charge is Q. The distance...
Question : State which type of thermodynamic system (Isolated, Closed, Open) the following are... Include in your answer which type of system they are relative to short and long time periods.
A list then followed.
I'm unsure about only one.
A thermal flask.
I know in the long term a...
Hey all, I'm looking for a version of steam/water thermodynamic properties for excel. I need it to be able to compute properties based on pressure and entropy. Something similar to the X Steam Tables (http://www.x-eng.com/XSteam_Excel.htm) would be awesome, but again, I need the ability to...
Homework Statement
Derive an expression for the isentropic compressibility of a solid (BETA sub S) in terms of isothermal compressibility (beta sub T) and other properties normally tabulated.
Homework Equations
β_T≝-1/V (∂V/∂P)_T
β_S≝-1/V (∂V/∂P)_S
The Attempt at a Solution
I...
As a practical matter, the internal energy of a system is treated as a state function of a the system and is concerned only with the kinetic energy of particles, not the potential energy. So for thermodynamic entropy, S=E/T, (S=entropy, T= absolute temperature) I'm considering E to be kinetic...
Hey guys, I'm having some trouble finding thermodynamic tables for n-pentane and n-butane. Does anybody know where I can find them, whether it be in books or (a trust able) online source?
Thanks.
Homework Statement
A rigid tank has a volume of 0.01m3. It initially contains saturated water at a temperature of 200°C and a quality of 0.4. The top of the tank contains a pressure-regulating valve that maintains the vapor at constant pressure. This system undergoes a process whereby it is...
Homework Statement
A balloon containing 2.00 x10^3 m3 of helium gas at 1.00 atm and a temperature of 15.0°C rises rapidly from ground level to an altitude at which the atmospheric pressure is only 0.900 atm. Assume the helium behaves like an ideal gas and the balloon's ascent is too rapid to...
Hopefully somebody can help me with this. I have a final exam next week, and the textbook we use along with my professor didn't do a good job explaining what happens in irreversible reactions.
More specifically, what differences are there between reversible and irreversible processes of...
Can you help me solution:
The PWR plant of Figure 6-6 operates under the conditions given in Table 6-6. Assume that the turbine and pump have isentropic effciencies of 85%.
1. Draw the temperature-entropy (T-s) diagram for this cycle .
2. Compute the ratio ,of the...
Dear friends,
I have a question regarding thermodynamic integration in the NPT ensemble.
Suppose I vary the parameter a from 0 to 1, where 0 is the reference state whose free energy I know and 1 corresponds to the state whose free energy I want to find out. then is the...
I am wondering why water is used instead of air for the cold temperature source for a thermo cycle. My guess is the higher specific heat, which means the condenser unit can be smaller, and the mass flow rate less, which reduces the overall cost.
Are there any other reasons to choose water...
Homework Statement
For Cyclohexane
Boiling point T_b = 80.1°C
P = 1atm
\Delta H_{vap} = 30.1 kJ/mol
Determine at phase change liquid to vapour, Changes in:
a)Entropy per mole
b)Gibbs free energy per mole
c)Internal energy per mole
assume ideal gas behaviour for the vapour...
Homework Statement
Assuming V is a function of P and T such that
V = V(P,T)
express the differential changes in volume due to differential changes in Temperature and pressure, what is the fractional/relative change?
Homework Equations
The Attempt at a Solution
since V is a...
Homework Statement
1 mole of a gas is burned completely burned in a constant-volume bomb calorimeter at 298 K, 5150 kJ of heat is evolved. Calculate the values delta U and delta H
Homework Equations
H = U + W
The Attempt at a Solution
I was lead to believe that you had to...
Homework Statement
Hi! I apologize in advance for my knowledge of vocabulary in this topic:)
OK, so we have a Melde-tube 55 cm long, T=293K, with the top of it open, and a 20cm Hg part cutting off 30cm of air when is equilibrium. The original problem asked how much we can heat the air so...
Homework Statement
The van der Waals’ equation of state for one mole of gas is given by
(P+a/V2)(V-b)=RT
where V is the molar volume at temperature T, and a and b are constants. The internal energy of the gas is given by
E=(3/2)RT-a/V
Initially, one mole of the gas is at a temperature T1...
Homework Statement
A steel tank of cross sectional area 3 m2 and height 16 m weighs 10,000 kg and is open at the top. We want to float it in the ocean so that it is positioned 10 m straight down by pouring concrete into its bottom. How much concrete should we use?
Homework Equations...
A rigid vessel of volume 0.1185 m3 contains one kg of steam‐water mixtures at 5 bar. If heat is
added to the vessel until the pressure reaches 20 bar. Sketch a suitable state diagram to represent the process.
How do i draw the state diag since pressure is not constant? So is this a case...
Homework Statement
A gas enters a compressor and is compressed isentropically. Does the specific enthalpy (h) increase or decrease as the gas passes from inlet to exit?
Homework Equations
\left(\frac{\partial{h}}{\partial{p}} \right)_s= v\qquad(1)
The Attempt at a Solution
Since...
how do you read of these tables to get them filled. Can you please show me how to do them not do them for me only please do 1 of each showing me how to do them for each. Doing past exams papers for the test coming up after summer and will need this one as it appears in most papers. The most...
Hello,
In my old papers, I could find a nice P-T diagram for Carbon Dioxide.
I am interrested in liquid-gas equilibrium data, specially enthalpy and internal enery.
Unfortunately, the diagram doesn't fit very well my current purpose.
Moreover, I would like to make more use of my computer...
Hey folks,
I am looking for something free to help me out here. I have experimental data that consists of the temperature and pressure of a gas over time. That is I have (T1,P1), (T2,P2),...(Tn,Pn) where n might be upward of a 500.
I would like to be able to determine the specific volume...
How to choose thermodynamic cycle for designing new jet engine?
While designing new jet engine what parameters are important for choosing thermodynamic cycle?
what other parameters are important for jet engine designing?
Homework Statement
When a sealed Thermos bottle of hot coffee is shaken, what changes, if any, takes place in the temperature of the coffee and its internal energy? Justify your answer.
Homework Equations
Internal energy = random kinetic energy + random potential energy
The Attempt...
In my opinion the nature of the second law of thermodynamic is probabilistic
and it sholud be formulated in a way which determine probability that given
proces occurs (the probability should depened on the tatal entropy change,
if its negative the proces is very unlikely but in principle...
Here are some general questions regarding my current reading. I am looking in my text at 2 equations for specific energy and specific enthalpy:
u = u(T,v)\qquad(1)
h = h(T,p)\qquad(2)
Question 1: Are not the properties fixed by any 2 independent priorities? Why have we chosen to...
I am reading through a thesis paper and it says that for a combustion process in which we have separated the chamber into 2 zones: burned and unburned ideal gas mixtures, if we know the pressure and equivalence ratio (ER) for the unburned ideal gas mixture, we can find all of its thermodynamic...
"Open" and "closed" in the geometrical sense vs the thermodynamic sense
Perhaps this is a silly question, but what is the relationship between the words "open" and "closed" in the geometrical sense (open, flat, closed universes) and in the thermodynamic sense (open and closed systems) in the...
I have some questions about thermodynamic potentials (internal energy U, enthalpy H, Helmholz free energy F, Gibbs free energy G):
1. The differentials of potentials:
dU<=TdS-pdV
dH<=TdS+Vdp
dF<=-SdT-pdV
dH<=-SdT+Vdp
Do this equations apply only for a single homogeneous system or can...