Passive solar tracker based in the differential thermal expansion of vertical strips

2019 ◽  
Vol 11 (4) ◽  
pp. 043701 ◽  
Author(s):  
Miguel Centeno Brito ◽  
José Mário Pó ◽  
Daniela Pereira ◽  
Fernando Simões ◽  
Roberto Rodriguez ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Solar Tracker ◽  
Differential Thermal Expansion ◽  
Passive Solar

Thermally Induced Synchronous Instability of a Radial Inflow Overhung Turbine: Part I

1997 ◽  
Author(s):  
H. B. Faulkner ◽  
W. F. Strong ◽  
R. G. Kirk
Keyword(s):  
Thermal Expansion ◽  
Operating Speed ◽  
Lateral Motion ◽  
Turbine Wheel ◽  
Thermally Induced ◽  
Lateral Dynamics ◽  
Morton Effect ◽  
Speed Range ◽  
Differential Thermal Expansion ◽  
Rotor Dynamic

Abstract This paper is in two parts, and concerns the lateral dynamics of a large turbocharger rotor with overhung wheels. Initial rotor dynamic analysis indicated no excessive motion in the operating speed range. However, testing showed excessive motion, which was initially traced to the radial-inflow turbine wheel becoming loose on the shaft, due to transient differential thermal expansion in the wheel on startup. The attachment of the wheel was modified to eliminate this problem. The discussion up to this point is in Part I of the paper, and the remainder is in Part II. The wheel attachment modification extended the range of satisfactory operation upward considerably, but excessive lateral motion was again encountered near the upper end of the operating speed range. This behavior was traced to thermal bowing of the shaft at the turbine end, known as the Morton Effect. The turbine end bearing was modified to eliminate this problem, and satisfactory operation was then achieved throughout the operating speed range.

Design of a novel passive solar tracker

Solar Energy ◽  
2004 ◽  
Vol 77 (3) ◽  
pp. 269-280 ◽  
Author(s):  
M.J. Clifford ◽  
D. Eastwood
Keyword(s):  
Solar Tracker ◽  
Passive Solar

Optimization of a Ceramic Circuit Board Clamp

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000394-000401
Author(s):  
David A. Glowka ◽  
Randy A. Normann
Keyword(s):  
Thermal Expansion ◽  
Fixed Point ◽  
Elevated Temperature ◽  
Design Optimization ◽  
Parametric Study ◽  
Material Selection ◽  
Circuit Board ◽  
Differential Thermal Expansion ◽  
Logging Tool ◽  
Clamping Pressure

This paper documents the design optimization of a board-mounting system for securing a ceramic or other heavy circuit board to the electronics chassis in a wireline logging tool. A clamp fixes the extreme lower end of the circuit board to the chassis while allowing the board and chassis to undergo differential thermal expansion above that fixed point, through the use of sliding board mounts. After developing equations that describe the stress, deflection, and thermal expansion of the clamp/board assembly, they are used to select the geometry and material options available in the design. Results of a parametric study are presented that demonstrate how material selection determines whether the clamping pressure on the circuit board improves or degrades at elevated temperature, and how the geometries of the clamp components affect the magnitudes of the forces, deflections, and setting torque of the clamp.

scholarly journals The Role of Calcite Dissolution and Halite Thermal Expansion as Secondary Salt Weathering Mechanisms of Calcite-Bearing Rocks in Marine Environments

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 911
Author(s):  
Javier Martínez-Martínez ◽  
Anna Arizzi ◽  
David Benavente
Keyword(s):  
Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Laboratory Simulation ◽  
Salt Weathering ◽  
Chemical Dissolution ◽  
Marine Environments ◽  
Thermal Cycles ◽  
Laboratory Simulations ◽  
Salt Crystallisation ◽  
Differential Thermal Expansion

This research focuses on the analysis of the influence of two secondary salt weathering processes on the durability of rocks exposed to marine environments: chemical dissolution of rock forming minerals and differential thermal expansion between halite and the hosting rock. These processes are scarcely treated in research compared to salt crystallisation. The methodology followed in this paper includes both in situ rock weathering monitoring and laboratory simulations. Four different calcite-bearing rocks (a marble, a microcrystalline limestone and two different calcarenites) were exposed during a year to a marine semiarid environment. Exposed samples show grain detachment, crystal edge corrosion, halite efflorescences and microfissuring. Crystal edge corrosion was also observed after the laboratory simulation during a brine immersion test. Calcite chemical dissolution causes a negligible porosity increase in all the studied rocks, but a significant modification of their pore size distribution. Laboratory simulations also demonstrate the deterioration of salt-saturated rocks during thermal cycles in climatic cabinet. Sharp differences between the linear thermal expansion of both a pure halite crystal and the different studied rocks justify the registered weight loss during the thermal cycles. The feedback between the chemical dissolution and differential thermal expansion, and the salt crystallisation of halite, contribute actively to the rock decay in marine environments.

Heat-Exchanger Tube-Sheet Design—2: Fixed Tube Sheets

1952 ◽  
Vol 19 (2) ◽  
pp. 159-166
Author(s):  
K. A. Gardner
Keyword(s):  
Thermal Expansion ◽  
Heat Exchanger ◽  
Tube Sheet ◽  
Heat Exchanger Tube ◽  
Shell Side ◽  
Side Pressure ◽  
Differential Thermal Expansion ◽  
Design Factors ◽  
Exchanger Tube ◽  
Design Pressure

Abstract It is shown that “fixed” tube sheets may be designed in exactly the same manner as “floating” tube sheets with the same boundary restraint, provided that a fictitious uniform “equivalent design pressure” is used in the calculations instead of the actual hydrostatic pressure. This equivalent pressure is evaluated in terms of tube-side pressure, shell-side pressure, differential thermal expansion, and the condition of boundary restraint. The design factors for all tube sheets presented in an earlier paper are shown to be well represented by very simple expressions when the fundamental design parameter xa becomes large.

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