摘要:

AbstractPhase‐change coatings have been applied to the axial‐clearance rotor‐stator cavity for the estimation of the transient heat transfer characteristics of the surface of the rotating disc. The tests were conducted for an air mass flow coefficientCw= 1220, a gap ratioG= 0.1, an axial‐clearance ratioGca= 0.05 and for rotational Reynolds numbers of Reϕ = 1 × 105and 2 × 105. The phase‐change coating used had a melting point of 38°C. From a video recording of the transient movement of the melt‐line on the rotor (coated with the phase‐change material) blown with heated air, it was possible to compute the heat transfer coefficients. The data reduction was made using the ‘semi‐infinite slab’ approximation to the governing one‐dimensional transient

ISSN:0363-907X    

DOI:10.1002/er.4440150602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA photogalvanic cell containing Azur C as the photosensitizer and EDTA as the reductant has been investigated for solar energy conversion. The photopotential and photocurrent generated by this cell were 879 mV and 75 μA, respectively. The effects of various parameters on the electrical output of the cell have been studied. The current/voltage (i/V) characteristics of the cell have also been observed, and a tentative mechanism for the generation of the photocurrent in the photogalvanic cell has been proposed. The performance of the cell was determined in darkness at its power point

ISSN:0363-907X    

DOI:10.1002/er.4440150603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe paper presents a modelling technique and a method for determination of the windmill torque loss coefficients of a multibladed windmill. First, a new model is presented of a multibladed windmill, and the windmill torque loss coefficients are defined. Next, a measuring method based on a recursive estimation technique is developed for determination of the values of these coefficients. The torque loss coefficients are estimated satisfactorily from the simulated data and experimental data for changes in wind speed. The validity of the windmill model and the proposed estimating technique are demonstrated.

ISSN:0363-907X    

DOI:10.1002/er.4440150604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe paper sets out an economic framework within which to judge the potential economic benefits of using newly discovered indigenous fuel reserves. It illustrates the method with extensive reference to the newly discovered deposits of lignite in Northern Ireland. For a long time, the lack of indigenous fuel supplies, together with some unfortunate decisions on fuel use, resulted in Northern Ireland having the highest energy costs of any region in the United Kingdom. Although not the bonanza it was originally thought to be, lignite offers the possibility of a secure source of fuel to power at least part of the local electricity supply system, the smallest isolated electricity supply system in western Europe.

ISSN:0363-907X    

DOI:10.1002/er.4440150605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThree types of conventional solar air heater are designed such that their heat absorbing areas and the pressure drops across them are equal for equal air mass flow rates per unit collector area. The results of thermal performance tests conducted simultaneously on these collectors, under the same environmental conditions, are presented.

ISSN:0363-907X    

DOI:10.1002/er.4440150606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA quantitative analysis of the long‐term field performance of a photovoltaic (PV) array has been made considering such field variables as solar insolation, temperature and long‐term degradation of a solar cell. It deals with (i) the numerical analysis of two degradation factors of a single crystal solar cell, namely, increased lumped series resistanceRsand decreased short circuit currentIsc, (ii) the field conditionVm—Imrelation, and (iii) the ratio ofImandIscfor a PV array. The value ofImhas been computed from the solution of a transcendental equation using Newton–Raphson approximation technique.This approach has been verified by field data obtained in Delhi, India, over a period of four years for the single crystal silicon PV modules (manufactured by CEL, India). It can be used for the study of the long‐term field performance of a polycrystalline and amorphous silicon

ISSN:0363-907X    

DOI:10.1002/er.4440150607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe new concepts of time‐varying stabilizer design via dynamic pole assignment and eigenstructure assignment are introduced in this paper. The theorem of dynamic pole assignment is obtained by employing the piecewise constant concept. By specifying the final eigenstructure, the parameters of the time‐varying stabilizer can be determined via output feedback. The optimal reduced order model is used to represent the dynamic system model. The effectiveness of this controller is evaluated, and examples of a one‐machine infinite‐bus system and a multimachine system, are given to illustrate the advantages and effectiveness of the proposed te

ISSN:0363-907X    

DOI:10.1002/er.4440150608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe paper addresses the design of a power system stabilizer using an optimal reduced order model whose state variables are torque angles and speeds. System damping can be improved using eigenvalue assignment, and the co‐ordination of stabilizers can be achieved through eigenvector assignment by maintaining system mode shape. The proportional‐integral PSS is derived via the optimal reduced order model instead of via the whole system model. The effectiveness of this stabilizer is evaluated, and this study reveals that the result of eigenstructure assignment is more stable and much better than in the assignment method based on the whole system model. A one‐machine infinite‐bus system and a multimachine system are given as examples to illustrate the advantages and effectiveness of the proposed approach. Results based on the whole system model are included for com

ISSN:0363-907X    

DOI:10.1002/er.4440150609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe paper addresses the problem of the estimation of ground losses from underground structures. Existing work has been limited to the cylinder and the sphere for steady state conditions. The numerical solution of the three‐dimensional equations for time‐dependent conditions requires a prohibitive amount of computing time. The present paper analyses a spherical underground structure with a periodic source at its centre and with periodic ground surface temperat

ISSN:0363-907X    

DOI:10.1002/er.4440150610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe paper presents a techno‐economic model to evaluate the performance of a hybrid solar still. For this, three different sources of auxiliary energy, namely electricity, kerosene, and liquefied petroleum gas (LPG) have been considered. To appreciate the model, numerical calculations have also been made using prevailing prices of different fuels in the Indian market for the climate of Delhi, Indi

ISSN:0363-907X    

DOI:10.1002/er.4440150611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY