tailieunhanh - Design and Optimization of Thermal Systems Episode 3 Part 7

Tham khảo tài liệu 'design and optimization of thermal systems episode 3 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 622 Design and Optimization of Thermal Systems in the operating conditions the user ambient conditions raw materials and other unpredictable parameters are used to leave an acceptable margin of safety. For instance a dimension obtained as 2 cm from the feasible or optimal design may be increased to 3 cm for safety giving a factor of safety of particularly if this dimension refers to the outer wall of a system and may fail. Higher safety factors are used if damage to an operator may result from leakage of radiation hot fluid high-pressure gases etc. This is particularly true in the design of nuclear reactors boilers furnaces and many other such systems where high temperatures and pressures arise. Therefore the design obtained on technical grounds is adjusted to account for safety of the user as well as of the materials and the system. Similarly environmental concerns can affect the design. Constraints are placed on the types of materials that can be used on temperature and concentration of discharges into the environment on maximum flow rates that may be used on types and amount of solid waste and so on. For instance chlorofluorocarbons CFCs are not allowed because of their effect on the ozone layer. The temperature of the cooling water from the condensers of a power plant that is discharged into a lake or a river is constrained to say within 10 C of the ambient water temperature by federal regulations. This imposes an important constraint on the design of the system. Similarly the concentration of pollutants and the flow rate of the fluid discharged into air are constrained by regulations to ensure a clean environment. Again these aspects arise as additional constraints on the design and must be taken into account. The legal issues are often related to federal and state regulations on waste disposal zoning procurement transportation security permits etc. and can generally be considered in terms of the cost incurred since these involve additional expenditures by