scholarly journals On the validity of representing hurricanes as Carnot heat engine

2008 ◽  
Vol 8 (5) ◽  
pp. 17423-17437 ◽  
Author(s):  
A. M. Makarieva ◽  
V. G. Gorshkov ◽  
B.-L. Li
Keyword(s):  
Water Vapor ◽  
Heat Input ◽  
Heat Engine ◽  
Thermodynamic Theory ◽  
Air Pressure ◽  
Atmospheric Process ◽  
Laws Of Thermodynamics

Abstract. It is argued, on the basis of detailed critique of published literature, that the existing thermodynamic theory of hurricanes, where it is assumed that the hurricane power is formed due to heat input from the ocean, is not physically consistent, as it comes in conflict with the first and second laws of thermodynamics. A quantitative perspective of describing hurricane energetics as that of an adiabatic atmospheric process occurring at the expense of condensation of water vapor that creates drop of local air pressure, is outlined.

Processes and Responses

2017 ◽  
Author(s):  
Jochen Rau
Keyword(s):  
Heat Engine ◽  
Cyclic Process ◽  
Free Enthalpy ◽  
Initial State ◽  
Thermodynamic Potentials ◽  
Grand Potential ◽  
Laws Of Thermodynamics ◽  
Cyclic Processes ◽  
Energy Exchanges ◽  
Thermodynamic Processes

Thermodynamic processes involve energy exchanges in the forms of work, heat, or particles. Such exchanges might be reversible or irreversible, and they might be controlled by barriers or reservoirs. A cyclic process takes a system through several states and eventually back to its initial state; it may convert heat into work (engine) or vice versa (heat pump). This chapter defines work and heat mathematically and investigates their respective properties, in particular their impact on entropy. It discusses the roles of barriers and reservoirs and introduces cyclic processes. Basic constraints imposed by the laws of thermodynamics are considered, in particular on the efficiency of a heat engine. The chapter also introduces the thermodynamic potentials: free energy, enthalpy, free enthalpy, and grand potential. These are used to describe energy exchanges and equilibrium in the presence of reservoirs. Finally, this chapter considers thermodynamic coefficients which characterize the response of a system to heating, compression, and other external actions.

scholarly journals IV. On the thermodynamic theory of steam-engines with dry saturated steam, and its application to practice

1859 ◽  
Vol 9 ◽  
pp. 626-628 ◽  
Keyword(s):  
Liquid Water ◽  
Practical Experience ◽  
Thermodynamic Theory ◽  
Steam Engine ◽  
Saturated Steam ◽  
Theoretical Conclusion ◽  
Saturated Vapour ◽  
Principal Effect ◽  
Laws Of Thermodynamics

In 1849 it was demonstrated, contemporaneously and independently, by Professor Clausius and the author of this paper, from the laws of thermodynamics, that when steam or other saturated vapour in expanding performs work, and receives no heat from without, a portion of it must be liquefied. That theoretical conclusion has since been confirmed by practical experience. The principal effect of the “steam-jacket” invented by Watt is to prevent that liquefaction. The presence of liquid water in any considerable quantity in the cylinder of a steam-engine acts injuriously, by taking heat from the steam while it is being admitted, and giving out that heat to the steam which is about to be discharged. Most of the heat so transferred is wasted.

Comment on Makarieva et al . ‘A critique of some modern applications of the Carnot heat engine concept: the dissipative heat engine cannot exist’

2010 ◽  
Vol 467 (2125) ◽  
pp. 1-6 ◽  
Author(s):  
Marja Bister ◽  
Nilton Renno ◽  
Olivier Pauluis ◽  
Kerry Emanuel
Keyword(s):  
Wind Speed ◽  
Heat Engine ◽  
Dissipative Heating ◽  
Dissipative Heat ◽  
External Objects ◽  
Laws Of Thermodynamics ◽  
Physical Laws ◽  
Work Done ◽  
Fundamental Physical ◽  
Engine Concept

Makarieva et al . (2010) assert that a dissipative heat engine is impossible and criticize earlier published work that they claim violates the laws of thermodynamics. Here we show that the earlier work does not violate fundamental physical laws and suggest that Makarieva et al . (2010) were misinterpreting expressions for wind speed as ones for work done on external objects. Moreover, we dispute their assertion that dissipative heating is necessarily compensated by a reduction of external heating.

A Mist Chamber for the Culture of Plants or Explant Segments

Weed Science ◽  
1970 ◽  
Vol 18 (2) ◽  
pp. 223-225 ◽  
Author(s):  
C. A. Beasley ◽  
W. P. Fox
Keyword(s):  
Water Vapor ◽  
Plant Pathogens ◽  
Air Pressure ◽  
Plant Organs ◽  
Vegetative Plant ◽  
Spray System ◽  
Different Types ◽  
Height Gauge ◽  
Mist Chamber ◽  
Condensation Tube

Versatile mist chambers, framed with aluminum and glass and having access from top and sides, permit culture of an extensive number of, and different types of, vegetative plant organs as well as seeds and plant pathogens. Pneumatic atomizing nozzles are staggered to permit division of the chamber, and the spray emitted can be regulated from each nozzle. The amount of water vapor emitted is regulated by changing the air pressure or siphon height. Gauge-monitored pressure regulators and solenoid valves control the air and spray system. Timing devices can be used to inject water vapor at desired intervals. Air passing through a condensation tube is recycled past cone heaters, providing temperature from ambient to 90 F, and a duct and baffle system provides uniformity of temperature throughout. A combination recorder and controller maintains the desired temperature.

Quantum Thermodynamics: An Example of Two-Level Quantum Machine

2014 ◽  
Vol 21 (01n02) ◽  
pp. 1440002 ◽  
Author(s):  
R. Alicki
Keyword(s):  
Simple Model ◽  
Heat Engine ◽  
Standard Formulation ◽  
Quantum Thermodynamics ◽  
Quantum Domain ◽  
Laws Of Thermodynamics

A simple model of microscopic thermal machine which can work as a heat engine or refrigerator is discussed. This model serves as a tutorial example of quantum thermodynamics and shows that with the proper definitions of fundamental thermodynamical notions the standard formulation of the laws of thermodynamics remains valid also in the quantum domain.

scholarly journals OPTIMAL EVAPORATING AND CONDENSING TEMPERATURES OF ORGANIC RANKINE CYCLE IN A HOT AND HUMID ENVIRONMENT

2016 ◽  
Vol 36 (1) ◽  
pp. 110-118
Author(s):  
UV Ihuoma ◽  
EO Diemuodeke
Keyword(s):  
Heat Input ◽  
Figure Of Merit ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Thermodynamic Theory ◽  
Development Environment ◽  
Evaporation Temperature ◽  
Humid Environment ◽  
Theoretical Procedure

This paper presents a thermodynamic analysis of an organic Rankine cycle (ORC) in a hot and humid environment. A theoretical procedure is proposed for the determination of the optimal evaporation temperature (OET) and optimal condensing temperature (OCT) of a subcritical ORC plant, which is based on thermodynamic theory; the heat input is selected as the objective function. The OETs and OCTs of 21 working fluids, which comprise wet, isentropic and dry fluids, are determined under given environmental conditions– hot and humid environment. The Engineering Equation Solver (EES) integrated development environment is used to optimize the heat input of the ORC plant. Results suggest that the wet fluids (namely R717, Methanol and Ethanol) have the potential of producing better thermodynamic figure of merit over the other fluid types.   http://dx.doi.org/10.4314/njt.v36i1.14

scholarly journals A critique of some modern applications of the Carnot heat engine concept: the dissipative heat engine cannot exist

2010 ◽  
Vol 466 (2119) ◽  
pp. 1893-1902 ◽  
Author(s):  
Anastassia M. Makarieva ◽  
Victor G. Gorshkov ◽  
Bai-Lian Li ◽  
Antonio Donato Nobre
Keyword(s):  
Heat Input ◽  
Heat Engine ◽  
External Heat ◽  
Mechanical Work ◽  
Physical Models ◽  
Carnot Cycle ◽  
Engine Model ◽  
Dissipative Heat ◽  
Internal Dissipation ◽  
Engine Concept

In several recent studies, a heat engine operating on the basis of the Carnot cycle is considered, where the mechanical work performed by the engine is dissipated within the engine at the temperature of the warmer isotherm and the resulting heat is added to the engine together with an external heat input. This internal dissipation is supposed to increase the total heat input to the engine and elevate the amount of mechanical work produced by the engine per cycle. Here it is argued that such a dissipative heat engine violates the laws of thermodynamics. The existing physical models employing the dissipative heat engine concept, in particular the heat engine model of hurricane development, need to be revised.

Rudolf Clausius

2020 ◽  
pp. 368-385
Author(s):  
Robert T. Hanlon
Keyword(s):  
Internal Energy ◽  
Heat Engine ◽  
Physical Property ◽  
Ideal Gas ◽  
Cyclic Process ◽  
Major Step ◽  
Laws Of Thermodynamics ◽  
Caloric Theory ◽  
Liquid Vapor

Clausius completed the heat engine analysis that Carnot started by eliminating the caloric theory on which it was based and replacing it with Joule’s heat–work equivalence. He proceeded to validate Carnot’s theory of the irrelevance of the working substance’s nature by proving equivalent performances between an engine based an ideal gas and one based on liquid–vapor water. Clausius embraced two principles that became forerunners of the 1st and 2nd Laws of Thermodynamics: 1) heat–work equivalence, and 2) heat must flow from hot to cold whenever work is done in a cyclic process. He also introduced a new physical property of matter he named U, which later became known as internal energy. In his work, Clausius took the first major step towards completion of thermodynamics.

Water Vapor and Mechanical Work: A Comparison of Carnot and Steam Cycles

2011 ◽  
Vol 68 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Olivier Pauluis
Keyword(s):  
Energy Source ◽  
Water Vapor ◽  
Relative Humidity ◽  
Latent Heat ◽  
Energy Transport ◽  
Heat Engine ◽  
Bowen Ratio ◽  
Carnot Cycle ◽  
The Impact ◽  
Steam Cycle

Abstract The impact of water vapor on the production of kinetic energy in the atmosphere is discussed here by comparing two idealized heat engines: the Carnot cycle and the steam cycle. A steam cycle transports water from a warm moist source to a colder dryer sink. It acts as a heat engine in which the energy source is the latent heat of evaporation. It is shown here that the amount of work produced by a steam cycle depends on relative humidity and is always less than that produced by the corresponding Carnot cycle. The Carnot and steam cycles can be combined into a mixed cycle that is forced by both sensible and latent heating at the warm source. The work performed depends on four parameters: the total energy transport; the temperature difference between the energy source and sink; the Bowen ratio, which measures the partitioning between the sensible and latent heat transports; and the relative humidity of the atmosphere. The role of relative humidity on the work produced by a steam cycle is discussed in terms of the Gibbs free energy and in terms of the internal entropy production.

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