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(4) A specialized knowledge in various circumstances, such as the properties of materials in corrosive atmospheres, at very low ( cryogenic ) temperatures, or at relatively high temperatures.
(5) A preparation for deciding wisely: (a) when to use manufacturer's catalogs, buying stock or relatively available items, and when custom design is necessary; (b) when empirical design is justified; (c) when the design should be tested in service tests before manufacture starts; (d) when special measures should be taken to control vibration and sound ( and others ).
(6) Some aesthetic sense, because the product must have "customer appeal" if it is to sell.
(7) A knowledge of economics and comparative costs, because the best reason for the existence of engineers is that they save money for those who employ them. Anything that increases the cost should be justified by, for instance, an improvement in performance, the addition of an attractive feature, or greater durability.
(8) Inventiveness and the creative instinct, most important of all for maximum effectiveness. Creativeness may arise because an energetic mind is dissatisfied with something as it is and this mind is willing to act.
Naturally, there are many other important considerations and a host of details. Will the machine be safe to operate? Is the operator protected from his own mistakes and carelessness? Is vibration likely to cause trouble? Will the machine be too noisy? Is the assembly of the parts relatively simple? Will the machine be easy to service and repair?
Of course, no one engineer is likely to have enough expert knowledge concerning the above attributes to make optimum decisions on every question. The larger organizations will have specialists to perform certain functions, and smaller ones can employ consultants. Nevertheless, the more any one engineer knows about all phases of design, the better. Design is an exacting profession, but highly fascinating when practiced against a broad background of knowledge.
In the early 1980s, engineers thought that massive research would be needed to speed up product development. As it turns out, less research is engineers to use available technology. Developing a revolutionary short steps is a safer and usually more successful approach to product development,
Shorter product development cycles are also beneficial in an engineering world in which both capital and labor are global. People who can design and manufacture various products can be found anywhere in the world, but containing a new idea is hard. Geographic distance is no longer a barrier to others finding out about your development six months into the process. If you’ve got a short development cycle, the situation is not catastrophic—as long as you maintain your lead. But if you’re in the midst of a six-year development process and a competitor gets wind of your work, the project could be in more serious trouble.
The idea that engineers need to create a new design to solve every problem is quickly becoming obsolete. The first step in the modern design process is to browse the Internet or other information systems to see if someone else has already designed a transmission, or a heat exchanger（Plate heat exchangers (PHEs) have been widely used in food processing, chemical reaction processes and many other industrial applications due to their high effectiveness, compactness, flexibility, and cost competitiveness. Furthermore, they have been introduced to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. Recently, a number of investigations on PHE were reported in the open literature. Unfortunately, most studies about PHE in the open literature were mainly focused on the singly-phase liquid-to-liquid heat transfer, especially for water [1-3]. There are rather limited data available for the design of PHEs used as evaporators and condensers. Recently, Yan and Lin [4,5] experimentally measured the evaporation and condensation heat transfer coefficients and frictional pressure drops for R-134a in a PHE. They showed that the evaporation heat transfer for R-134a flowing in the PHE was much higher than that in circular tubes, and both the evaporation heat transfer coefficient and pressure drop increased with the vapor quality. Moreover, the rise in the heat transfer coefficient with the vapor quality was larger than that in the pressure drop.