Month: December 2022

Violation of Kelvin–Plank Statement by Violating Clausius Statement From Figure 1.13 (a) let us assume that a heat pump receives heat QL from low temperature reservoir at TL and supplies it to high temperature sink at TH without any external work, thus violating the Clausius statement. A larger quantity of heat (QH + QL) is supplied to heat engine (by high temperature source at TH) which… Continue reading Equivalence of Kelvin–Planck and Clausius Statement

It is impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a lower temperature body to higher temperature body. In other words, a refrigerator cannot be operated without external work supplied to refrigeration system. Heat flows from high temperature to low temperature reservoir.… Continue reading Clausius Statement

The Kelvin–Plank statement of the second law of thermodynamics refers to a thermal reservoir. A thermal reservoir is a system of infinite heat capacity that remains at a constant temperature even though energy is added or removed by heat transfer. A reservoir is an idealization, of course, but such a system can be approximated in… Continue reading Kelvin–Planck Statement

Second law of thermodynamics overcomes the limitations of first law of thermodynamics. First law of thermodynamics does not tell how much of heat is changed into work. Second law of thermodynamics shows that the total heat supplied to a system cannot be transferred solely into the work using single reservoir, i.e., some part of heat… Continue reading THE SECOND LAW OF THERMODYNAMICS

First law of thermodynamics does not tell about the following:

In some flow process, mass flow rate is not steady but varies with respect to time. In such a case, the difference in energy flow is stored in system as ΔEv. Rate of energy increase = Rate of energy inflow − Rate of energy outflow Example 1.14: An air conditioning system, as shown in Figure 1.8, handling 1… Continue reading Variable Flow Process

Steady Flow Process In a steady flow process, thermodynamic properties at any section remain constant with respect to time; it can vary only with respect to space. A schematic diagram of steady flow process is shown in Figure 1.7. Figure 1.7 Schematic Diagram of Steady Flow Process From continuity equation: Energy balance equation: This is known as… Continue reading Application of First Law of Thermodynamics in Steady Flow Process and Variable Flow Process

In this process, the law is governed by PVn = constant. Work done during adiabatic process From first law of thermodynamics Example 1.2: The initial pressure and temperature of 1 mole of an ideal gas are 1 MPa and 380 K, respectively. It is heated at constant pressure till the temperature is doubled and then is allowed to expand… Continue reading Polytropic Process

In this process, heat transfer is equal to zero. Work done during adiabatic process From first law of thermodynamics

In this process, temperature remains constant, i.e., ΔT = 0. This is also known as isothermal process. From first law of thermodynamics