Next Article in Journal
Generalised Measures of Multivariate Information Content
Previous Article in Journal
Sociophysics Analysis of Multi-Group Conflicts
Previous Article in Special Issue
Energy and Exergy Evaluation of a Two-Stage Axial Vapour Compressor on the LNG Carrier
Open AccessArticle

Second Law Analysis for the Experimental Performances of a Cold Heat Exchanger of a Stirling Refrigeration Machine

FEMTO-ST, Energy Department, Univ. Bourgogne Franche-Comté, CNRS Parc technologique, 2 avenue Jean Moulin, 90000 Belfort, France
*
Author to whom correspondence should be addressed.
Entropy 2020, 22(2), 215; https://doi.org/10.3390/e22020215
Received: 23 December 2019 / Revised: 8 February 2020 / Accepted: 11 February 2020 / Published: 14 February 2020
(This article belongs to the Special Issue Carnot Cycle and Heat Engine Fundamentals and Applications)
The second law of thermodynamics is applied to evaluate the influence of entropy generation on the performances of a cold heat exchanger of an experimental Stirling refrigeration machine by means of three factors: the entropy generation rate N S , the irreversibility distribution ratio ϕ and the Bejan number B e | N S based on a dimensionless entropy ratio that we introduced. These factors are investigated as functions of characteristic dimensions of the heat exchanger (hydraulic diameter and length), coolant mass flow and cold gas temperature. We have demonstrated the role of these factors on the thermal and fluid friction irreversibilities. The conclusions are derived from the behavior of the entropy generation factors concerning the heat transfer and fluid friction characteristics of a double-pipe type heat exchanger crossed by a coolant liquid (55/45 by mass ethylene glycol/water mixture) in the temperature range 240 K < TC < 300 K. The mathematical model of entropy generation includes experimental measurements of pressures, temperatures and coolant mass flow, and the characteristic dimensions of the heat exchanger. A large characteristic length and small hydraulic diameter generate large entropy production, especially at a low mean temperature, because the high value of the coolant liquid viscosity increases the fluid frictions. The model and experiments showed the dominance of heat transfer over viscous friction in the cold heat exchanger and B e | N S 1 and ϕ → 0 for mass flow rates m ˙ 0.1 kg.s−1. View Full-Text
Keywords: Stirling cycle; refrigerator; heat exchanger; second law; entropy production Stirling cycle; refrigerator; heat exchanger; second law; entropy production
Show Figures

Figure 1

MDPI and ACS Style

Djetel-Gothe, S.; Lanzetta, F.; Bégot, S. Second Law Analysis for the Experimental Performances of a Cold Heat Exchanger of a Stirling Refrigeration Machine. Entropy 2020, 22, 215.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop