scholarly journals Energy Efficient Control of the Dehumidification Process in Heat Exchangers with Air Bypass

2019 ◽  
Vol 111 ◽  
pp. 04035 ◽  
Author(s):  
Stephan Kusche ◽  
André Badura
Keyword(s):  
Heat Exchanger ◽  
State Space ◽  
Heat Exchangers ◽  
Basic Concept ◽  
Energy Efficient ◽  
Reduction Method ◽  
Krylov Space ◽  
Air Stream ◽  
Efficient Control ◽  
Energy Consuming

This paper deals with an energy efficient approach for the dehumidification process of supply air. The basic concept consists of an air bypass, which separates the airstream. Later the unprocessed air is mixed with the conditioned air. This mixing allows one to avoid the energy consuming reheating of the air stream. Application of this concept demands for a sophisticated controller. In this case a state space controller is designed. Therefore, the underlying model for the heat exchanger is derived and a Krylov Space based reduction method is applied. This model is broadened for the bypass. The overall linear model is derived via numerical linearization.

scholarly journals Dynamic electromagnonic crystal based on artificial multiferroic heterostructure

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Alexey B. Ustinov ◽  
Andrei V. Drozdovskii ◽  
Andrey A. Nikitin ◽  
Alexander A. Semenov ◽  
Dmytro A. Bozhko ◽  
...  
Keyword(s):  
Energy Efficient ◽  
Small Time ◽  
Experimental Realization ◽  
Microwave Frequencies ◽  
Field Control ◽  
Efficient Control ◽  
Energy Consuming ◽  
Multiferroic Heterostructures ◽  
Magnonic Crystals ◽  
Multiferroic Heterostructure

Abstract One of the main challenges for the modern magnonics, which, as opposed to the conventional electronics, operates with quanta of spin waves in magnetically ordered materials—magnons—is energy efficient control of magnon transport on small time and space scales. The magnon propagation in a time-dependent periodic spatial potentials—dynamic magnonic crystals—paves a way to this aim. To date, dynamic manipulation of the magnonic crystals has been realized with electric current and optic control influence. However, both approaches show limited potential for reduction in energy consumption and miniaturization of magnonic circuits. Voltage (or electric field) control of magnon currents promises to be fast and low energy consuming. It can be achieved in ferrite-ferroelectric (multiferroic) heterostructures, where strong coupling of magnons and microwave photons constitutes new quasiparticles called electromagnons. Here, we present an experimental realization of a voltage-controlled dynamic electromagnonic crystal operating with electromagnons at microwave frequencies.

ENERGY EFFICIENT PIPE HEAT EXCHANGER FOR WASTE HEAT RECOVERY FROM EXHAUST FLUE GASES

2017 ◽  
Vol 16 (5) ◽  
pp. 1107-1113 ◽  
Author(s):  
Andrei Burlacu ◽  
Constantin Doru Lazarescu ◽  
Adrian Alexandru Serbanoiu ◽  
Marinela Barbuta ◽  
Vasilica Ciocan ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Energy Efficient ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Flue Gases ◽  
Pipe Heat

scholarly journals Low enthalpy geothermal energy: borehole heat exchangers (BHE). Geological and geothermal supervision during active construction in support of the energy certification of buildings - ESBE certification plan

2012 ◽  
Author(s):  
Lorenzo Cadrobbi ◽  
Fioroni Daniele ◽  
Alessandro Bozzoli
Keyword(s):  
Energy Conservation ◽  
Heat Exchangers ◽  
Energy Efficient ◽  
Geothermal Energy ◽  
Energy Requirements ◽  
Effective Coverage ◽  
Correct Execution ◽  
Environmental Technologies ◽  
Borehole Heat Exchangers ◽  
Ongoing Monitoring

This article draws on the experience matured while working with low-enthalpy geothermic installations both in the design and executive phase as well as ongoing monitoring, within the scope of energy conservation as it relates to building and construction. The goal is to illustrate the feasibility of adopting the ESBE certification protocol (Certification of Energy Efficient Low-Enthalpy Probes) aimed at optimizing the harnessing of local geothermic resources to satisfy the energy requirements of a building, measured against the initial investment. It is often the case, in fact, that during the course of a construction project for a given low-enthalpy installation, we verify incompa tibilities with the local geologic and geothermic models, which, if inadequate during construction, can compromise the proper functioning of the installation and its subsequent operation. To this end, the ESBE method, which adheres to the governing environmental regulations, and which takes its cue from technical statutes within the sector, permits us to validate via verification, simulations and tests, the geothermic field probes used in construction in an objective and standardized manner, thereby joining and supporting the most recent protocols for energy certification of buildings (LEED 2010, CASACLIMA 2011, UE 20120/31 Directive). ESBE certification operates through a dedicated Certifying Entity represented by the REET unit (Renewable Energies and Environmental Technologies) of FBK (Bruno Kessler Foundation) of Trento. The results obtained by applying the ESBE method to two concrete cases, relative to two complex geothermic systems, demonstrate how this protocol is able to guarantee, beyond the correct execution in the field of geothermic probes, an effective coverage of the energy requirements of the building during construction adopting the best optimization measures for the probes in keeping with the local geological and geothermic model.

Energy efficient and controlled flow processing under microwave heating by using a millireactor-heat exchanger

AIChE Journal ◽  
2011 ◽  
Vol 58 (10) ◽  
pp. 3144-3155 ◽  
Author(s):  
N. G. Patil ◽  
A.I.G. Hermans ◽  
F. Benaskar ◽  
J. Meuldijk ◽  
L. A. Hulshof ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Microwave Heating ◽  
Energy Efficient ◽  
Controlled Flow

Identification and energy efficient control for a building: Getting inspired by MPC

2015 ◽  
Author(s):  
Eva Zacekova ◽  
Matej Pcolka ◽  
Jaroslav Tabacek ◽  
Jiri Tezky ◽  
Rush Robinett ◽  
...  
Keyword(s):  
Energy Efficient ◽  
Efficient Control

Analysis of the Thermal Stress at the Tubesheet in Floating-Head or U-Tube Heat Exchangers

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Jiuyi Liu ◽  
Caifu Qian ◽  
Huifang Li
Keyword(s):  
Thermal Stress ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Influence Factors ◽  
Area Ratio ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Numerical Tests ◽  
Hole Area

Thermal stress is an important factor influencing the strength of a heat exchanger tubesheet. Some studies have indicated that, even in floating-head or U-tube heat exchangers, the thermal stress at the tubesheet is significant in magnitude. For exploring the value, distribution, and the influence factors of the thermal stress at the tubesheet of these kind heat exchangers, a tubesheet and triangle arranged tubes with the tube diameter of 25 mm were numerically analyzed. Specifically, the thermal stress at the tubesheet center is concentrated and analyzed with changing different parameters of the tubesheet, such as the temperature difference between tube-side and shell-side fluids, tubesheet diameter, thickness, and the tube-hole area ratio. It is found that the thermal stress of the tubesheet of floating-head or U-tube heat exchanger was comparable in magnitude with that produced by pressures, and the distribution of the thermal stress depends on the tube-hole area and the temperature inside the tubes. The thermal stress at the center of the tubesheet surface is high when tube-hole area ratio is very low. And with increasing the tube-hole area ratio, the stress first decreases rapidly and then increases linearly. A formula was numerically fitted for calculating the thermal stress at the tubesheet surface center which may be useful for the strength design of the tubesheet of floating-head or U-tube heat exchangers when considering the thermal stress. Numerical tests show that the fitted formula can meet the accuracy requirements for engineering applications.

Application of Equipartition of Entransy Loss Principle in Heat Exchangers

2012 ◽  
Vol 629 ◽  
pp. 699-703
Author(s):  
Chun Sheng Guo ◽  
Wen Jing Du ◽  
Lin Cheng
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Optimization Design ◽  
Loss Rate ◽  
Plate Heat Exchanger ◽  
Loss Minimization ◽  
Plate Heat ◽  
Entransy Loss ◽  
Heat Exchanges ◽  
Minimization Approach

The entransy loss minimization approach for the heat exchanger optimization design was established by Guo Z Y; the study based Guo Z Y’s works, found relationship between the entransy loss uniformity and the heat exchanger performance and the expression of the local entransy loss rate for heat convection was derived, numerical results of the heat transfer in a chevron plate heat exchanger and helix baffle heat exchanger show that the larger entransy loss uniformity factor appear in about Re=2000 and the entransy loss uniformity factor of chevron plate heat exchanges higher than helix baffle one.

Development of Heat Exchanger Fouling Model and Preventive Maintenance Diagnostic Tool

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
H. Zabiri ◽  
V. R. Radhakrishnan ◽  
M. Ramasamy ◽  
N. M. Ramli ◽  
V. Do Thanh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Predictive Model ◽  
Diagnostic Tool ◽  
Preventive Maintenance ◽  
Heat Exchangers ◽  
Waste Heat ◽  
A Priori ◽  
Transfer Efficiency ◽  
Heat Transfer Efficiency

The Crude Preheat Train (CPT) is a set of large heat exchangers which recover the waste heat from product streams back to preheat the crude oil. The overall heat transfer coefficient in these heat exchangers may be significantly reduced due to fouling. One of the major impacts of fouling in CPT operation is the reduced heat transfer efficiency. The objective of this paper is to develop a predictive model using statistical methods which can a priori predict the rate of the fouling and the decrease in heat transfer efficiency in a heat exchanger in a crude preheat train. This predictive model will then be integrated into a preventive maintenance diagnostic tool to plan the cleaning of the heat exchanger to remove the fouling and bring back the heat exchanger efficiency to their peak values. The fouling model was developed using historical plant operating data and is based on Neural Network. Results show that the predictive model is able to predict the shell and tube outlet temperatures with excellent accuracy, where the Root Mean Square Error (RMSE) obtained is less than 1%, correlation coefficient R2 of approximately 0.98 and Correct Directional Change (CDC) values of more than 90%. A preliminary case study shows promising indication that the predictive model may be integrated into a preventive maintenance scheduling for the heat exchanger cleaning.

The Effect of Longitudinal Heat Conduction on Periodic-Flow Heat Exchanger Performance

1964 ◽  
Vol 86 (2) ◽  
pp. 105-117 ◽  
Author(s):  
G. D. Bahnke ◽  
C. P. Howard
Keyword(s):  
Heat Conduction ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Zero Element ◽  
General Purpose ◽  
Periodic Flow ◽  
Gas Streams ◽  
Flow Heat ◽  
Area Use ◽  
Significant Figures

A numerical finite-difference method of calculating the effectiveness for the periodic-flow type heat exchanger accounting for the effect of longitudinal heat conduction in the direction of fluid flow is presented. The method considers the metal stream in crossflow with each of the gas streams as two separate but dependent heat exchangers. To accommodate the large number of divisions necessary for accuracy and extrapolation to zero element area, use was made of a general purpose digital computer. The values of the effectiveness thus obtained are good to four significant figures while those values for the conduction effect are good to three significant figures. The exchanger effectiveness and conduction effect have been evaluated over the following range of dimensionless parameters. 1.0⩾Cmin/Cmax⩾0.901.0⩽Cr/Cmin⩽∞1.0⩽NTU0⩽1001.0⩾(hA)*⩾0.251.0⩾As*⩾0.250.01⩽λ⩽0.32

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