Search

To the Editor: It was great to see the diesel engine finally getting noticed in what overall was a nice article, 'A New Dawn for Diesel,' in the January issue, [...]

The advantages of designing heat exchangers in the laminar-flow regime are discussed from a theoretical standpoint. It is argued that laminar-flow designs have the advantages of reducing thermodynamic and hydrodynamic irreversibilities, and hence increasing system efficiency. More concretely, laminar-flow heat exchangers are free from the turbulence-induced vibration common in conventional heat exchangers, and can thus offer longer life and greater reliability.The problems of manufacturing heat exchangers suited to laminar flow are discussed. A method of manufacture is outlined that allows compact, modular design. Experience with this method of manufacture is described. Experimental results with a prototype heat exchanger bank are presented; these results show good agreement with theory at moderate levels of effectiveness (75-85%), but fall below predicted values at higher levels. It is argued that this discrepancy results from flow maldistribution. The problems of fouling and flow maldistribution are briefly discussed, and some possible applications are mentioned.

Presents a letter to the editor in response to the article "A Second Look at Nuclear Power," by Paul Lorenzini in the spring 2005 issue.

Presents a letter to the editor related to the advantages of using biofuels compared to hydrogen.

A letter to the editor is presented in response to the article regarding algae oil in the January 26, 2009 issue.