Skip to main content

Thermodynamics Lecture - 6

 BASIC PROBLEMS OF FIRST LAW OF THERMODYNAMICS

1. During a Flow process 5 KW paddle wheel work is supplied while the internal energy of the system increases in one minute as 200 KJ. Find the Heat transfer when there is no other form of Energy Transfer

Given Data:

Workdone (W) = -5 Kw

Internal Energy (U) = 200 KJ / Min

(Need to Convert in Sec)

= 200 / 60

= 3.33 KJ /s

To Find :

Heat Transfer (Q)

Solution:

First Law of Thermodynamics:

Q = W+U

= - 5+3.33

= -1.67 KW

(“-” Sign Indicates that the heat is transferred from the system)

2. A liquid of mass 18 Kg is heated from 25 ° C to 85 ° C. How much is heat transfer is required? Assume Cp for water is 4.2 KJ/Kg.K

Given Data:

m = 18 Kg

T1 = 25 ° C = 25 +273K = 298 K

T2 = 85 ° C = 85 + 273 = 358 K

To find :

Heat transfer Q

Solution:

Q = m.Cp(T2- T1)

= 18 x 4.2 x (358 – 298)

= 4536 KJ

Labels:

Comments

Post a Comment

Popular posts from this blog

Thermodynamics - Lecture - 11 - Unit - 3 - Steam Properties and Problems

Problem: 1   A vessel of volume 0.04 m 3 contains a mixture of saturated water and steam at a temperature of 250°C The mass of the liquid present is 9 kg. Find the pressure, mass, specific volume, enthalpy, entropy and internal energy. Given data: V=0.04m 3 T= 250°C m 1 = 9 kg To find: p, m, v, h, S, and U   Solution: From Steam Tables corresponding to 250°C, v f =v 1 = 0.001251 m/kg V g = V s = 0.050037 m/kg p= 39.776 bar   Total volume occupied by the liquid, V 1 = m 1 v 1 = 9 x 0.001251 = 0.0113 m 3 Total volume of the vessel, V = Volume of liquid + Volume of steam V 1 +V s V s =0.0287 m 3   Mass of steam, m s = V s / V s   =0.0287 / 0.050037 =0.574 kg Mass of mixture of liquid and steam, m=m 1 +m s = 9+ 0.574 = 9.574 kg   Total specific volume of the mixture, v = V / m   = 0.04 /9.574 = 0.00418 m 3 /kg   We know that, v=v f +x V fg V fg = v g - v f 0.00418 = 0.001251 + x (0.05003...
Post a Comment
Read more

ME8691 COMPUTER AIDED DESIGN AND MANUFACTURING

  ME8691 COMPUTER AIDED DESIGN AND MANUFACTURING UNIT I INTRODUCTION Text Book Link: https://drive.google.com/file/d/1jcXUoP-axkNTd2S-AbiWhbUMCyqB643D/view?usp=sharing UNIT II GEOMETRIC MODELING Text Book Link: https://drive.google.com/file/d/1FMm2whgkPH0YdIz6z84csG9DonJJxJSR/view?usp=sharing UNIT III CAD STANDARDS Text Book Link: https://drive.google.com/file/d/1KBsbpx-PMudXsLasu2G6624ctD1ZgoMk/view?usp=sharing UNIT IV FUNDAMENTAL OF CNC AND PART PROGRAMING Text Book Link: https://drive.google.com/file/d/1LSSaf9Hr0olLyiyqE2nJNLzxs-lvjByo/view?usp=sharing UNIT V CELLULAR MANUFACTURING AND FLEXIBLE MANUFACTURING SYSTEM (FMS) Text Book Link: https://drive.google.com/file/d/1PxFAEx8YoFha_G_ZrDM4xOZpT91KPcbe/view?usp=sharing CAD&M Notes Link: https://drive.google.com/file/d/1dra3jcfkrF02HxXPLcgVyIcA234yPLQ2/view?usp=sharing CAD&M QB Link: https://drive.google.com/file/d/18fIwlt-Kbn_jVdJcJL97fSysuTfLINp1/view?usp=sharing      
Post a Comment
Read more

Engg Thermodynamics - Lecture - 13 - Unit - 4 - Ideal Gas and Real Gas & TD Relations

 Ideal Gas Imaginary Substance Obeys the law of PV=RT At low Pressure and High Temperature – density of gas Decreases Real Gas At High Pressure – Gas start to Deviate from Ideal Gas Measuring of Deviation – Compressibility Factor PV=ZRT Z=PV / RT Z = Vactual / Videal For Ideal Gas Z = 1 For Real Gas Z > 1 Important Laws (Ideal Gas) Boyle's Law (constant temperature) P = constant / V Charles Law (constant pressure) V = constant x T Gay-Lussac’s Law (constant volume) P = constant x T THE ENTHALPY OF ANY SUBSTANCE h=u+pv for an ideal gas h=u+RT h=f(T) dh=du+RdT since R is constant ∆h=∆u+R∆T =Cv∆T+R∆T = (Cv+R)∆T Since h is a function of T only, Cp=(∂h/∂T)p Entropy change of an ideal gas: (Eqn – 1) From the general property relations Q = W+ U Tds=du+pdv And for an ideal gas, du=CvdT, dh=CpdT, and pv=RT, the entropy change between any two states 1 and 2 may be computed as given below ds=du/T+p/Tdv =CvdT/T+Rdv/v S2-s1=Cv ln T2/T1+R ln v2/v1 . Entropy change of an ideal gas: (Eqn -2) Fr...
Post a Comment
Read more