摘要:

AbstractCycles of gas turbine devices using liquid and gas fuels with chemical heat regeneration are considered. A thermodynamic analysis of one of these schemes was carried out using energy and enthalpy balances. The behaviour of the cycle was investigated as a function of the pressure in the chemical regenerator (Pch) and in the turbine (PT), and the temperature in the chemical catalytic regenerator (Tch). Calculations were carried out atPT⩽ 10.0 MPa,Pch⩽ 2.0 MPa andTch⩽ 600 K. As a result, it was shown that the thermal efficiency ηTof the cycle with chemical regeneration of the exhaust gases increased by about 12%. The dependences of ηTonPchandTchwere o

ISSN:0363-907X    

DOI:10.1002/er.4440170402

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe paper presents exact analytical solutions for periodic radial heat conduction through an inhomogeneous hollow circular cylinder for a certain class of thermal conductivity profile. The exact analytical solutions for some of these profiles (including linear and quadratic) are compared with those obtained by considering the cylindrical medium to be made up of a number of homogeneous layers with different thermal conductivities, varying from layer to layer, and using the layered‐structure (or matrix‐multiplication) method. The numerical results arrived at by the layered‐structure method converge rapidly (with increasing number of layers considered) to the values obtained from the exact analytical solutions. This gives confidence in the application of the layered‐structure method to periodic heat conduction through an inhomogeneous hollow cylinder. Assuming the inhomogeneous hollow cylinder to be made up of a number of cylindrical layers with a linear profile of thermal conductivity has also been shown to be a more effective alternative method of considering any type of inhomogeniety; it saves computation time, as the rate of converegence is much higher than for the homogeneous‐layer structure method. Numerical results are presented in the form of elements of a 2 × 2 matrix, relating the sinusoidal steady‐state temperature and the heat flux on the two sides of

ISSN:0363-907X    

DOI:10.1002/er.4440170403

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe paper presents the exact analytical solutions for periodic radial heat conduction through an inhomogeneous hollow sphere for a certain class of thermal‐conductivity profile. The exact analytical solutions for some of these profiles, (including linear and quadratic) have been compared with those obtained by considering the spherical medium to be made up of a number of homogeneous layers with different thermal conductivities, varying from layer to layer, and using the layered‐structure (or matrix‐multiplication) method. The numerical results arrived at by the layered‐structure method converge rapidly (with increasing number of layers considered) to the values obtained from the exact analytical solutions. It strengthens the confidence in applying the layered‐structure method to the case of periodic heat conduction through an inhomogeneous hollow cylinder. Considering the inhomogeneous conducting medium to be made up of a number of spherical layers with a linear profile of thermal conductivity has been shown to be a more effective alternative method of accounting for any type of inhomogeniety; and it saves computation time, as the rate of convergence is much higher than for the homogeneous‐layered structure method. The numerical results have been presented in the form of elements of a 2 × 2 matrix, relating the sinusoidal steady‐state temperature and heat flux of the two surfaces of the

ISSN:0363-907X    

DOI:10.1002/er.4440170404

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe sawdust stove, classically known for several decades, is considered here in a scientific study. The poor ignition characteristics and smoky start up are related to improper geometric dimensions. Based on a parametric study, the startup procedure and the dimensions of the stove were modified to achieve a smooth start up. Also, the range of acceptable fuels was enlarged to include tiny unprocessed dry twigs, weeds and wood sticks o the extent of about 50%, with the rest being sawdust‐like material. The efficiency of the stove was measured to be 30–40%, depending on the relative size and shape of the vessel and the power level of the stove. A simple procedure for designing this class of stove for various power levels, as well as burning times, is presented. A new concept of multiport design is also discus

ISSN:0363-907X    

DOI:10.1002/er.4440170405

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe authors compare various flow diagrams for high temperature chemical heat pumps (HTCHP) based on the reversible cyclohexane‐dehydrogenation/benzene‐hydrogenation reactions. A new technological flow diagram for HTCHP is suggested. The peculiarity of this diagram is a multipurpose use of hydrogen‐permeable membranes. A comparative thermodynamic analysis of the flow diagrams under consideration is undertaken in order to examine the influence of various factors on the heat efficiency and coefficient of performance of the heat pump. It is shown that the use of the hydrogen‐permeable membranes in principle allows one to improve the performance of the HTCHPs and to extend the field of their application in comparison with the HTCHPs based on the flow diagrams suggested

ISSN:0363-907X    

DOI:10.1002/er.4440170406

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

年代:1993

数据来源: WILEY

摘要:

AbstractA procedure using the concept of the utilizability function for estimating the long‐term performance of direct‐coupled photovoltaic water‐pumping systems is presented. A modified utilizability function, based on radiation statistics, is developed, and the monthly‐averaged daily amount of water is simply es

ISSN:0363-907X    

DOI:10.1002/er.4440170407

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

年代:1993

数据来源: WILEY

摘要:

AbstractAzur dyes were used with mannitol (MANN) and nitrilotriacetic acid (NTA) in photogalvanic cells for the purpose of solar energy conversion and storage. The photocurrents and photopotentials generated by cells containing azur A, mannitol and NTA systems were 80 μA and 347 mV, respectively. The effects of various parameters on the electrical output, the fill factor, the conversion efficiency and the performance of the cells in the dark were studied

ISSN:0363-907X    

DOI:10.1002/er.4440170408

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

年代:1993

数据来源: WILEY

摘要:

AbstractAn experimental study is conducted to investigate the fuel‐injection‐pressure and engine‐speed effects on the performance and exhaust emissions of a naturally aspirated four‐stroke indirect‐injection (IDI) diesel engine with a swirl combustion chamber. The influence of the injection pressure and the engine rotational speed on fuel consumption, exhaust‐gas temperature, exhaust smokiness and exhaust‐gas emissions (nitrogen oxides and unburned hydrocarbons) is examined, following a detailed experimental investigation. Empirical easy‐to‐use correlations are produced, expressing the variation of the various parameters with injection pressure, by applying a regression analysis on the curves fitting the relevant experimental data. Theoretical aspects of diesel fuel spray progress (atomization, evaporation and mixing), combustion and emissions formation are used for the interpretation of the observed

ISSN:0363-907X    

DOI:10.1002/er.4440170409

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of energy conservation measures for a typical two‐storey residential building in Saudi Arabia are studied. The analysis shows that insulating the walls and the roof (15 mm‐thick insulation) results in a significant reduction in the peak cooling load (>23%) and the annual energy consumption (>27%). Hence, a significant saving in customer and government equivalent uniform annual cost (EUAC) will be observed. The effects of additional measures, such as reducing the glazing area and the infiltration rate, are also repor

ISSN:0363-907X    

DOI:10.1002/er.4440170410

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

年代:1993

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440170411

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

年代:1993

数据来源: WILEY