ISSN:0145-7632    

DOI:10.1080/01457638108939597

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Information on the transient response of heat exchangers is essential to produce the optimum heat exchanger operation for the required function. A transient response analysis is presented for a heat exchanger with an infinite capacitance fluid on the shell side. The inlet temperature of the finite capacity fluid is stepped, and the heat exchanger response is represented by the change in the temperature of this fluid at the outlet of the tubes. The results cover all practical combinations of the dependent parameters and are presented as a set of charts. Results of previous workers in this field are discussed. Their charts cover a very restricted range of heat transfer conditions and are therefore of limited use. In addition, assumptions have been incorporated into their analyses which result in major discrepancies.

ISSN:0145-7632    

DOI:10.1080/01457638108939598

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The need to save energy in power producing and power consuming systems and the fact that evaporative cooling is the most efficient method for heat rejection led to the design and testing of a model of a special cooling tower, fn this hybrid system an evaporative condenser is being built into the cooling tower and the advantages of evaporative cooling are combined with those of a wet cooling tower, causing a lower condensing temperature or saving heat transfer area or both. The present work not only deals with the development of a practical model of a cooling tower module but also further develops, modifies and consolidates a computer program originally designed for horizontal finned or bare tube condensers. These modifications are associated with the vertical tube condenser in the hybrid tower considered in this work. It is shown that the performance of the model tower can be predicted by use of this computer program, as previously shown by Leidenfrost and Korenic for a different geometry. It is further shown that either the performance of a scaled-up hybrid tower can be predicted or a tower geometry can be sized for given heat rejection needs, based on inlet air state, water flow rate, and system geometry.

ISSN:0145-7632    

DOI:10.1080/01457638108939599

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A quasi-finite-element model of a multipass shell-and-tube heat exchanger is developed after the method of Gaddis and SchlUnder. The present model includes time-dependent inlet conditions and heat exchange. It is therefore applicable as a tool in system modeling for dynamic processes involving this type of heat exchanger. Under steady-state conditions, the present model reduces to that of Gaddis and SchlUnder.

ISSN:0145-7632    

DOI:10.1080/01457638108939600

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

While flowing a kerosene-type gas turbine fuel through a direct-resistance heated tube, a condition was found which resulted in a tube wall temperature profile with two peaks near the tube entrance. The downstream peak gradually diminished as deposits formed inside the tube and only one peak remained after seven hours. On the basis of existing analytical studies and experimental data pertaining to heat transfer in the entrance region of tubes, it was concluded that the temperature profile can be divided into five regions: development of the thermal boundary layer, appearance of secondary flows, fully developed thermal boundary layer, transition to turbulent flow and turbulent flow. Deposits increased the tube roughness and reduced the length required for laminar-turbulent transition.

ISSN:0145-7632    

DOI:10.1080/01457638108939601

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The computerized information retrieval techniques available to those involved in heat transfer engineering are reviewed. The various types of information contained in on-line data bases, the means of accessing it, and the potential benefits to be gained from its use are discussed.

ISSN:0145-7632    

DOI:10.1080/01457638108939602

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

An operationally convenient methodology is presented for relating economic costs to entropy generation. This methodology, in the hands of the heat exchanger designer, allows an interaction with the system designer to gain insights into the trade-offs allowed between the thermodynamic irreversibilities of flow friction, heat transfer, heat leakage, and mixing. The methodology starts with a recognition of the appropriate individual irreversibilities, then relates the individual costs to system rating and energy penalties by thermodynamic arguments. The analysis loop is closed by considerations related to reduction of the individual irreversibilities in a cost-effective way. In contrast, the usual energy or “exergy” analysis provides an answer for the overall costs of the collective irreversibilities. This does not provide the engineer with the insight needed to minimize the individual irreversibilities in a cost-effective manner,

ISSN:0145-7632    

DOI:10.1080/01457638108939603

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor