机械设计英文文献和中文翻译(5)
The above literature review clearly reveals that heat transfer in PHE has been studied mainly for single-phase flow, especially for water. Very few data are available for the phase change heat transfer characteristics associated with the PHEs. Although R-410A is one of the most likely substitute for R-22, the two-phase heat transfer data for R-410A are still scarce. To continue our previous study on the phase change heat transfer for R-134a in PHE [4,5], the saturated flow boiling heat transfer characteristics and pressure drop for refrigerant R-410A flow in a vertical PHE are investigated experimentally in this study. In addition, empirical correlations will be developed for predicting the corresponding heat transfer coefficient and friction factor for R-410A boiling in the PHE.）at is close to what you need. Through these information systems, you may discover that someone already has manufacturing drawings, numerical control programs, and everything else required to manufacture your product. Engineers can then focus their professional competence on unsolved problems.
In tacking such problems, the availability of high-powered personal computers and access to the information highway dramatically enhance the capability of the engineering team and its productivity. These information age tools can give the team access to massive databases of material properties, standards, technologies, and successful designs. Such pretested designs can be downloaded for direct use or quickly modified to meet specific needs. Remote manufacturing, in which product instructions are sent out over a network, is also possible. You could end up with a virtual company where you don’t have to see any hardware. When the product is completed, you can direct the manufacturer to drop-ship it to your customer. Periodic visits to the customer can be made to ensure that the product you designed is working according to the specifications. Although all of these developments won’t apply equally to every company, the potential is there.
Custom design used to be left to small companies. Big companies sneered at it—they hated the idea of dealing with niche markets or small-volume custom solutions. “Here is my product,” one of the big companies would say. “This is the best we can make it—you ought to like it. If you don’t, there’s smaller company down the street that will work on your problem.”
Today, nearly every market is a niche market, because customers are selective. If you ignore the potential for tailoring your product to specific customers’ needs, you will lose the major part of your market share—perhaps all of it. Since these niche markets are transient, your company needs to be in a position to respond to them quickly.
The emergence of niche markets and design on demand has altered the way engineers conduct research. Today, research is commonly directed toward solving particular problems. Although this situation is probably temporary, much uncommitted technology, developed at government expense or written off by major corporations, is available today at very low cost. Following modest modifications, such technology can often be used directly in product development, which allows many organizations to avoid the expense of an extensive research effort. Once the technology is free of major obstacles, the research effort can focus on overcoming the barriers to commercialization rather than on pursuing new and interesting, but undefined, alternatives.
When viewed in this perspective, engineering research must focus primarily on removing the barriers to rapid commercialization of known technologies. Much of this effort must address quality and reliability concerns, which are foremost in the mind of today’s consumers. Clearly, a reputation for poor quality is synonymous with bad business. Everything possible—including thorough inspection at the end of the manufacturing line and automatic replacement of defective products—must be done to assure that the customer receives a properly functioning product.