APPLIED THERMODYNAMICS FOR SECOND YEAR / THIRD SEMESTER EEE DEPT. UNIT I BASIC CONCEPTS INTRODUCTION Thermodynamics is defined as the branch of science which deals with the relations between energy and heat. These relations are governed by the laws of thermodynamics. These laws are based on the principle of energy conversion. It states that energy can be changed from one form to another but the total energy remains constant. In other words energy cannot be created or destroyed. APPLICATIONS OF THERMODYNAMICS • • • • • • Power plants IC engines Turbines Compressors Refrigeration Air-conditioning UNITS AND DIMENSIONS All physical quantities are characterized by dimensions. Dimensions of physical quantities may be defined as the properties in terms of quality not of magnitude by which a physical quantity may be described. Length (L), area (A)and volume (V)are all different dimensions which describe certain measurable characteristics of an object, e.g., A=L2 and V=L3 The arbitrary magnitudes assigned to the dimensions are called as units. In other words, a unit is a definite standard by which a dimension is to be measured. The primary or fundamental dimensions are length L in m, mass m in kg, time in sec and temperature T in K. The secondary or derived dimensions are velocity V in m/s, Energy E in J and volume V in m these are expressed in terms of primary dimensions. SYSTEM OF UNITS The most common system of unit is metric system SI, which is also known as the International System. In this text, the SI (System International) system of units has been used. Energy: Energy is defined as the capacity to do work. The various forms of energy are heat energy, mechanical energy, electrical energy and chemical energy. Unit of energy is Nm or Joule (J) and kWh. 1 kWh = 3.6 x 106 J The energy per unit mass is defined as specific energy whose unit is J/kg. Force: Force acting on a body is defined by Newton s second law of motion. According to this law, force is proportional to the product of mass and acceleration. When a force of one Newton applied to a body having mass of one kilogram, gives it an acceleration of one m/s. The unit of force is Newton (N). 1 N = l kgm/s Weight of a body (W) is the force with which the body is attracted to the centre of the earth. It is the product of its mass (m) and the acceleration due to gravity. i.e., Work: Work is defined as the work done when the point of application of 1 N force moves through a distance of 1m in the direction of the force, whose unit is Joule or Nm. The amount of work (W) is the product of the force (F) and the distance moved (L), W = F×L. Power: Power is defined as the rate of energy transfer or the rate of work. The unit of power is watt (W) 1N m/s = 1 MW = Pressure: Pressure is defined as the force per unit area exerted whose unit is N/m2 which is also known as Pascal (Pa) and for larger pressures, kPa (Kilo Pascal) and MPa (Mega Pascal) are used. Other units for pressure not in the SI units but commonly used are bar and standard atmosphere (atm) 0.1 MPa = 100 kPa = 105Pa 105 N/m = 1 bar 1 atm = 101 .325 kPa = 1.01325 bar 1J/s =1W 106 Kw W= mg (Value of g = 9.81 m/s at sea level) Mostly pressure of a fluid is measured by gauge which gives pressure relative to atmospheric pressure and is called as gauge pressure. In thermodynamic analysis one is mostly concerned with absolute pressure which is the pressure exerted by a system on its boundary. For pressures above atmospheric Pabsolute = pgauge + patm For pressures below atmospheric, the gauge pressure will be negative and is called as vacuum. U-tube manometer which is used to measure pressure, the two arms of the tube are connected to two containers which are at p and p pressures. The tube is filled with a fluid having density and h is the difference in the heights of the fluid columns. By the hydrostatics principle, P1-P2 = Where hg p2 in N/m2 is in kg/m3 h in m, g in m/s2 and then p1 Fig:1(a). For pressure above atm Temperature: Fig:1(b). For pressure below atm Temperature is defined as the degree of coldness or hotness of a body. When heat is added to the body, its temperature increases and when heat is removed from the body, its temperature decreases. Temperature is the thermal condition of a body on which its capacity of transferring heat to or receiving heat from other bodies depends. Thus the temperature determines direction, in which the heat flow will take place, Units of temperature are degree Celsius, degree Kelvin Temperature K = Temperature º C + 273 Under standard temperature and pressure (STP) conditions the temperature of a gas is taken as 15°C and the pressure as 760 mm of mercury. Under normal temperature and pressure (NTP) conditions the temperature of a gas is 0°C and the pressure as 760 mm of mercury. Specific Heat: Specific heat of a substance is defined as the quantity of heat required to raise the temperature of unit mass substance to one degree. Average specific heat, Where Q is heat interaction kJ, T is Temperature difference K and m is mass kg. If the state of the substance is liquid or solid there is only one specific heat. For the case of gaseous substances there are two specific heats, they are: 1. Specific Heat at Constant Volume: When the volume of the gas is constant the quantity of heat required to raise the temperature of unit mass of gas to one degree is termed as specific heat of gas at constant volume which is denoted by Cv 2. Specific Heat at Constant Pressure: When the heat is supplied at constant pressure the quantity of heat required to raise the temperature of unit mass of gas to one degree is termed as specific heat of gas constant pressure which is denoted by Cp CLASSICAL APPROACH MACROSCOPIC AND MICROSCOPIC APPROACH The behavior of one matter can be studied from macroscopic and microscopic points of view. v The macroscopic approach is only concerned with overall effect of the individual molecular interactions. v The microscopic point of view concerned with every molecule and analysis of collective molecular action is carried out by statistical techniques. For example, pressure is a macroscopic quantity, which is defined as the normal force exerted by a system against unit area of the boundary, i.e., the pressure exerted on the vessel is equal to the mean change of momentum of all the molecules exerted perpendicular to unit area of the boundary. This approach is not related with individual molecular action. This pressure can be measured by using pressure gauge. The microscopic approach is used to explain some matter which otherwise difficult to understand by macroscopic approach. THERMODYNAMIC SYSTEM AND SURROUNDINGS A thermodynamic system is a region in space or any matter or specified quantity of matter within a prescribed boundary on which we concentrate. The other matters outside of the boundary are known as surroundings. As shown in Fig.2(a) the system and surroundings are separated by boundary. The boundary may be real or imaginary one. The system is classified into three: • • • Closed System Open System Isolated System Closed System: In this system, the boundaries are closed so that there is no mass transfer. But there may be energy transfer into or from the system, while mass remains constant. This is also known as control mass. e.g., bomb calorimeter. Open System: In this system, the boundaries are not closed and mass and energy transfer may take place through the opening(s) in the boundary. This is also known as control volume. e.g., turbines and compressors. Fig:2(a)A thermodynamic system,(b)Closed system,(c) Open System, (d) Isolated system Isolated System: This system is not affected by surroundings. In this there is no mass or energy transfer across the boundary of the system. WORKING MEDIUM: In most of the devices the working medium is gas or vapor. It is important to know the properties and behavior of the working medium to observe and analyze the working of devices. At various pressures and temperatures the properties of the working fluid can be determined by using pure substance concept. • • The pure substance is defined as a substance that has a fixed chemical composition, e.g., water, nitrogen, helium and carbon-di-oxide. A mixture of two or more pure substances is also called as pure substance as long as the chemical composition is same. A mixture of liquid air and gaseous air cannot be called as pure substance because the mixture is not chemically homogeneous due to different condensation temperatures of the components in air at specified pressure. THERMODYNAMIC EQUILIBRIUM A system is said to be in a state of thermodynamic equilibrium if there is no change in the microscopic properties at all points in the system. For thermodynamic equilibrium, the following three types of equilibrium conditions have to be satisfied. Mechanical Equilibrium: A system is said to be in a state of mechanical equilibrium if there is no unbalanced force with in the system or between the system and the surroundings. Chemical Equilibrium: A system is said to be in a state of chemical equilibrium if there is no chemical reaction or transfer of matter from one part of the system to another. Thermal Equilibrium: A system is said to be in a state of thermal equilibrium if there is no change in any property of the system when the system is separated by a diathermic wall from its surroundings. Diathermic wall defined as a wall which allows heat to flow. STATE, PROPERTIES AND PROCESSES: • • State of a system is the condition of the system at any particular moment. It may be identified by the properties such as pressure, temperature and volume, etc. The property can be measured while the system is at a state of equilibrium. In any operation there is a change in system properties which is called the change of state. A series of changes in the system between initial state and final state is called the path of change of state. • When the path is specified completely the change of state followed by the working medium as it liberates, transfers, transforms or receives energy is called as process. A series of state changes or process undergone by a system such that the final state is identical with the initial state is defined as a thermodynamic cycle. • Fig .2.1(a) A process Fig .2.1 (b) A cycle In order to describe a system it is necessary to know the quantities and characteristics of the system which are known as properties. The properties are classified as extensive properties and intensive properties. • Properties which are related to mass are called as extensive or extrinsic properties, e.g., volume, energy, etc. If mass increases the value of extensive Properties will increase the properties which are independent of the mass of the system are called as intensive or intrinsic properties, e.g., temperature, pressure, velocity, density, etc. • Extensive properties per unit mass are known as specific extensive properties which are nothing but intensive properties, e.g., specific volume, specific energy, density, etc. Properties may also be classified into two types. They are fundamental properties and thermodynamic properties. • • Properties which are measured directly are called as fundamental properties, e.g., pressure, volume, temperature, etc. Properties which cannot be measured directly but in closed cycle the working medium is recirculated with in the system. In open cycle the working substance is exhausted to the atmosphere after the process. ZEROTH LAW OF THERMODYNAMICS: The zeroth law of thermodynamics states that if two bodies are in thermal equilibrium with a third body, then they are also in thermal equilibrium with each other. Fig: 3 Concept of Zeroth law Let us consider the temperature equality concept to three systems say, A, B and as shown in Fig.3. The system A consists of a mass of gas enclosed in a vessel fitted with a thermometer and the system B is a cold iron body. When A and B are brought in contact, after some time they attain a common temperature and are then said to exist in thermal equilibrium. Now the system is brought into contact with a third system C, again A and C attain thermal equilibrium, then system B and C will show no further change in properties when brought into contact. That is system A is in thermal equilibrium with system B and also separately with system C. Then B and C will be in thermal equilibrium with each other. This law provides the basis for temperature measurement. FIRST LAW OF THERMODYNAMICS The first law of thermodynamics states that a closed system executing a cycle in which the initial state and final state are same . i.e., The net work delivered to the surroundings is proportional to the net heat taken from the surroundings. That is heat and work is mutually conversible. Since energy can neither be created nor destroyed, the total energy associated with energy conservation remains constant. Mathematically, Where dw is net work delivered during the process and dq is net heat supplied during the process. FIRST LAW APPLIED TO CLOSED SYSTEM As shown in Fig3.2. let us consider a closed system which undergoes a cycle, in which x and y is two arbitrary properties of the system. According to first law of thermodynamics for a cyclic process, algebric sum of t is proportional to algebric sum of heat transferred. i.e., Q1-2 is proportional to Q2-1 This is applicable if the system involves more heat and work transfers at different points on the boundary. Where Q and W represent infinitesimal elements of heat and work transfer respectively. As no fundamental distinction between the unit of heat and the unit of work J can be neglected from the equation. Internal Energy: The energy E is the sum of Kinetic Energy (KE), Potential Energy (PE) and Internal Energy (U). The internal energy is due to the motion of the molecules and it changes with change in temperature. For a non flow and closed system, the kinetic and potential energy terms are zero, and then the energy will be The term E is the change in internal energy For an isolated system both Q and W are zero, the change in energy is also zero. Q= 0; W= 0; E=0 For reversible non flow process the work DISPLACEMENT WORK The most common example of mechanical work encountered in thermodynamic system is that associated with a process in which there is a change in volume of a system under pressure. Let the volume of the fluid within the moving boundary be v1 and pressure be p1. In p-v diagram, point-1 represents initial state. If the working medium expands and moves the piston to top dead centre (TDC) from bottom dead centre (BDC), the work will be done by the working medium. After expansion at state 2, pressure is decreased and volume increased. Since the system undergoes expansion process, it is represented by the curve 1 - x - y - 2 in p-V diagram as shown in Fig.4 Fig: 4. Displacement work The change of state from x to y, a very small change of state in which pressure is almost constant during the change, then the force acting on the movable boundary F× x = p-V During this piston moves to a distance dL and the work done = force × distance traveled. dW where dV= A×dL The total work at the moving boundary is = pA×dL = p×dV • When the work is done by the system, it is called as positive work. This is represented by the sign plus, +W indicated the work done by the system. e.g., expansion. When the work is done on the system, it is called as negative work. - W indicates the negative work. e.g., compression. • PATH FUNCTION AND POINT FUNCTION A non-flow process is one in which the gas is neither be supplied nor rejected across the boundary of the system. The system moves from state 1 to state 2 through two different paths A and B, as shown in Fig 5. Fig. 5.Path Function Each curve represents the work for each process, these two paths gives two different work values even though states 1 and 2 are identical, the work delivered to the shaft depends upon the particular function, so the work is called as path function. The differentiation of path function is inexact or imperfect. But the thermodynamic properties are point functions, because they depend on the end states and independent of the path which the system follows. The differentiation of point functions is exact or perfect differentials, e.g., change in pressure p2 p1 and change in volume V2- V1. APPLICATION OF FIRST LAW TO NON - FLOW PROCESS: NON - FLOW PROCESSES It is the process in which the substance does not leave the system, but energy only crosses the boundary in the form of work and heat. Non - flow processes are classified under two groups. They are a. Reversible non-flow processes b. irreversible non-flow processes. REVERSIBLE NON-FLOW PROCESSES (CLOSED SYSTEM): The following non-flow processes are reversible 1. 2. 3. 4. 5. Constant volume (isochoric) process Constant pressure (Isobaric) process Adiabatic (Isentropic) process Polytropic process : : : : V = constant; n = p = constant; n = 0 T= constant; n = 1 PV = constant; n = PVn = constant; n=n Constant temperature (Isothermal) process : Where p is pressure, V is volume, T is temperature, n is index of compression or expansion and is adiabatic index. Reversible Constant Volume Process: When volume remains constant during the execution of a process, the process is called as constant volume process. As shown in Below the system contains unit mass and state one in pV diagram represents the system state before the heating processes. State 2 represents the state of system after heating process. Applying the first law of thermodynamics The rise in heat causes rise in internal energy and loss of heat decreases the internal energy. APPLICATION OF FIRST LAW TO FLOW PROCESS: Most of the systems which are related to power generation are open systems in which the mass crosses the boundary of the system, and after doing the work it leaves the system. Flow processes are classified into two types, they are • • Steady flow process Non-steady flow process STEADY FLOW PROCESS A steady flow process is one in which the mass flow rate at the entry and at the exit is constant. At any point in the system the properties of the fluid do not change with time, e.g., compressor, turbines, nozzles, etc. Assumptions made in the analysis of a steady flow process are, 1. Mass flow rate through the system remains constant. 2. Composition of fluid is uniform 3. State of the fluid at any point in the system remains constant. 4. Work and heat are the only interaction between the system and surroundings. STEADY FLOW ENERGY EQUATION As stated in the law of conservation of energy the sum of total energy exerting the system is equal to the sum of total energy leaving the system. Thus there is no change in stored energy. Let m - mass flow rate in kg/s, - absolute pressure in N/m2, v - specific volume in m3/kg, V - velocity in m/s, Z - elevation above the datum in m, u - specific internal energy in J/kg, Q - heat into the system in J and W- work output in J. Fig: 6.Steady flow process Assumptions made are Mass flow in Energy in Total energy in = = = Mass flow out Energy out Total energy out at entry (Potential energy + Kinetic energy + Internal energy + Heat energy) (Potential energy + Kinetic energy + Internal energy + Work) at exit PE1 + KE1 + U1 + Q = PE2 + KE2 + U2 + W = This is the steady flow energy equation and all the energy values are in Watts. The steady flow energy equation can be written in mass basis as given below. Hence the energy values are in J/kg Mass flow in= Mass flow out m1 = m2 We know m = Where the density of fluid ρ = ρ= 1 1 = specific volume υ mass and volume for unit mass A1V1 AV = 2 2 υ1 υ2 UNSTEADY FLOW PROCESS An unsteady flow process is one in which the mass flow rate at the entry and exit of the system is not equal in a given time, and there is no change in stored energy of the system. Let Eout Ein be the change in flow energy and E change in stored energy. Based on first law SECOND LAW OF THERMODYNAMICS LIMITATIONS OF FIRST LAW • • The first law of thermodynamics states that, heat and work are mutually convertible during any cycle of a closed system. But in actual practice all forms of energy cannot be changed into work and the first law does not give any conditions under which conversion of heat into work is possible. The law does not specify the direction of the process under consideration. The limitations of first law are discussed below. • The following examples are based on the first law of thermodynamics and these processes only proceed in certain direction but not in the reverse direction. § Let T1 and T2 be the temperatures of two bodies where T1 is greater than T2 If these bodies are brought in contact with each other but are separated from surround- rigs, heat will flow from hot body (T1) to cold body (T2) till the temperature of both bodies are equal. But the reverse process is not possible, i.e., flow of heat from lower temperature body to higher temperature body. In an automobile moving at a certain speed, if the brakes are applied to stop the automobile means, the brakes get hot by the conversion of automobile s kinetic energy into heat. However, it will be observed that reversal of the process in which the hot brakes were to cool off and give back its internal energy to the automobile, causing it to move on the road. But this is impossible. § § SECOND LAW OF THERMODYNAMICS • KELVIN-PLANK STATEMENT OF SECOND LAW It is impossible to construct an engine which operates on cycle to receive heat from a single reservoir and produce net amount of work. Kelvin - Plank statement related to heat engines . In other words, no engine operating in cycles can convert all the heat energy into work, but there will be some loss of heat energy to the surroundings. Thus 100% efficient engine is not possible. Fig:7. Possible engine and not possible engine Possible engine is one in which a part of heat is rejected to the cold reservoir, which is supplied from the hot reservoir and the difference between the heat supplied and heat rejected is equal to work done. • CLAUSIS STATEMENT OF SECOND LAW Clausis statement is related to refrigerators or heat pumps. The Clausis statement is expressed as follows: It is not possible to construct a system that operates in a cycle and transfers heat from a colder body to a hotter body without the aid of an external agency. In other words, heat can not flow itself from a colder body to a hotter body . Based on this, the hot reservoir at T1 temperature and the cold reservoir at T2 temperature are shown in Fig: 8. The heat pump which takes mechanical work to transfer heat continuously from sink to source. Fig:8. External work required for heat flow from sink to source PERPETUAL MOTION MACHINE OF SECOND KIND (PMM II) Perpetual motion machine of second kind is one which operators in a cycle and delivers an amount of work equal to heat extracted from a single reservoir at an uniform temperature. Such 100% efficiency violates the second law of thermodynamics as according to Kelvin - Plank Statement. It is not possible to construct a machine which could extract heat from a single reservoir and convert it into equivalent amount of work. HEAT ENGINE Heat engine is defined as a machine which is used to convert heat energy into work in a cyclic process . The definition of heat engine covers both rotary and reciprocating machines. The working fluid should undergo cyclic process and periodically should return to its initial state. Fig: 9. Steam power plant as heat engine Fig: 9. shows a steam power plant which is an example of heat engine cycle. In the boiler high pressure steam is generated and the steam expands in the turbine and doing external work W exhaust steam from turbine is condensed in the condenser thereby releasing heat and the water is pumped back to the boiler to complete the cycle. Thus the boiler, turbine, condenser and the pump separately in a power plant can not be regarded as heat engine because they are engines since they are part of the cycle. Combination of these components is a heat engine since they complete the cycle. EFFICIENCY OF HEAT ENGINE Performance of a heat engine is obtained by its thermal efficiency which is the ratio of net work output to heat supplied . A part of heat supplied is converted into work and the rest is rejected. Let Q1 be heat supplied, Q2 be heat rejected, Wt be turbine work and Wp be pump work (Fig: 10.) As per the first law of thermodynamics Fig: 10. Heat engine Efficiency of the heat engine η= Network output Heat supplied HEAT PUMP Heat pump is defined as a device which transfers heat from a low temperature body to a high temperature body when it is working in a cycle (Fig:11). For heat pump the efficiency term is replaced by the co-efficient of performance (COP) which as an index of performance of heat pump to differentiate it from heat engine. COP of the pump is given by COP (heat pump) = Heating effect Work done Fig: 11. Heat pump If a heat pump is used to transfer heat from low temperature reservoir T2 to high temperature reservoir T1 in order to maintain T2 < T1 then the COP of the refrigerator is given by COP ref = Refrigerating effect Work input CARNOT CYCLE The Carnot cycle has four reversible processes, of which two are frictionless isothermal processes and two frictionless adiabatic processes. Figure.12 shows the p-V and T-s diagram of the Carnot cycle. • Process 1-2 represents reversible isothermal expansion, Heat Q is supplied at constant temperature T and this is equal to the work done during the process. V2 V1 Heat supplied Q1 = • P1V1ln Process 2-3 represents reversible adiabatic expansion, there is no heat transfer takes place. The work is done at the cost of internal energy. The temperature becomes T2 at T3 Fig.12 Carnot cycle • Process 3-4 represents reversible isothermal compression in which Q2 heat is rejected isothermally at T2. The air is compressed up to point 4 at constant temperature. Heat rejected • Process 4-1 represents reversible adiabatic compression in which the system returns back to the initial state and the temperature of air increases from. T2 to T1 There is no heat transfer and work is done on the air. Net work done = (Heat supplied) - (Heat Rejected) Efficiency of Carnot cycle = (Net work done / Heat supplied) CARNOT THEOREM The Carnot principles are the two conclusions regard to the thermal efficiency of ideal and natural (actual) heat engines. They are expressed as follows: • The efficiency of an actual (irreversible) heat engine is always less than the efficiency of an ideal (reversible) heat engine operating between the same two reservoirs. All the reversible (ideal) heat engines operating between the same two reservoirs will have the same efficiency. • CLAUSIS IN EQUALITY While applying second law of thermodynamics to processes the second law leads to the definition of a new property called entropy. Entropy is an abstract property, and it is difficult to give a physical description of it. The uses of entropy in common engineering processes provide the best understanding of it. The second law may be stated to be the law of entropy. The cyclic integral of dQ/T in above equation is always less than or equal to zero. Inequivality of Clausis is the basis of the definition of entropy. Entropy is a nonconserved property by which it differs from energy. This inequality is valid for all cycles, viz., and reversible or irreversible. The symbol φ denotes that the integration is to be performed over the entire cycle. Any heat transfer from or to a system can be considered to consist of differential amounts of heat transfer then the cyclic integral of dQ/T can be viewed as the sum of all these differential amounts of heat transfer divided by the absolute temperature at the boundary. CONCEPT OF ENTROPY ENTROPY AS A PROPERTY OF A SYSTEM Entropy of a substance is a thermodynamic property which increases with the addition of heat and decreases with the removal of heat. Entropy itself cannot be defined but the change in entropy can be defined in a reversible process, i.e., the quantity of he received or rejected divided by the absolute temperature of the substance measures the change in entropy. A small amount of heat dQ is added to the system causing the entropy to increase by ds and T is the absolute temperature. The change in entropy absolute temperature. If the total quantity of heat Q be added to a substance at constant temperature then the increase in entropy due to the addition of heat is given by ds = Q T Q T T × ds s1 − s2 = From the definition of entropy dQ = By integrating the equation the total heat added can be obtained as ENTROPY - A POINT FUNCTION Entropy has got one value for each point of temperature or pressure or volume. So it is a point function. The change in entropy during a thermodynamic process depend only on the initial and final conditions irrespective of the path. In solving problems the change in entropy is considered with the assumption if the entropy of all substances is zero at the ice-point, i.e., the entropy is positive if the temperature is above 0°C and negative if the temperature is below 0° C. Entropy is expressed as kJ/kgK, since, it has the dimension of heat/mass and temperature. There are many instruments to measure temperature, pressure, etc., but there no such instruments as yet to measure entropy. ENTROPY OF A REVERSIBLE CYCLIC PROCESS Let us consider a system undergoing a reversible process from state 1 to state along the path A and then from state 2 to the original state 1 along the path B as shown in Fig.13. Fig. 13. Reversible cyclic process between two fixed states CHANGE IN ENTROPY OF A PERFECT GAS Let m kg of gas carryout a process. At the initial state 1 let the pressure, temperature, entropy and volume are p1, T1, s1 and V1 respectively. The gas is heated in any manner such that at its final state 2 pressure, temperature, entropy and volume be p2, T2, s2 and V2 respectively. From the law of conservation of energy This is the change in entropy in terms of volume and temperature. This can be expressed in terms of pressure and volume by applying gas equation as JAYAM COLLEGE OF ENGINEERING AND TECHNOLOGY DHARMAPURI DEPARTMENT YEAR / SEM SUBJECT : EEE : SECOND/ THIRD : ME1211 / APPLIED THERMODYNAMICS ASSIGNMENT NO 1 Unit 1 Basic concepts and Laws of Thermodynamics PART A 1. State first law of thermodynamics? 2. State Zeroth law of thermodynamics? 3. What is meant by Perpetual Motion Machine of first kind ? 4. State the statements of second law of thermodynamics? 5. If pvn=C represents a general thermodynamic process, name the processes when n has values of 0, 1, and . 6. What are the types of thermodynamic properties? 7. Explain the thermodynamic equilibrium? Explain. 8. What is meant by Perpetual Motion Machine of second kind ? 9. State Carnot s theorem. 10. Define Clausis Inequality. PART B 1. Derive then expression for work and heat during constant volume and constant pressure process. 2. 3. 4. Derive then expression for work and heat isothermal and isentropic process. Derive the steady flow energy equation. A cycle heat engine operates between a source temperature of 800 C and a sink temperature of 30 C. What is the least rate of heat rejection per KW net output of engine? 5. 2 kg of air compressed according to the law pV1.3 = constant from a pressure of 1.8 bar and temperature of 30 C to a pressure of 25.5 bar. Calculate a) The final volume and temperature. b) Work done c) Heat transferred d) Change in entropy.
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