Mechanical work requirement

Specific heat The amount of heat (or mechanical work) required to raise the temperature of a unit mass of a substance one degree Celsius. In the case of gases there are two specific heats, according as to whether the heating takes place at constant pressure or at constant volume. 

Interlock testing is performed on a periodic basis, usually every 12 months, following detailed written test procedures. The test procedure for each safety interlock defines the actions, including the approval system and the mechanical work required to ensure reliability. These procedures cover the testing activity from the process measurement device to the final element, which is often a control valve. [26]... 

Process costs are influenced by various factors which are mutually dependent, so that it is not initially clear which extraction and separation conditions are the most favourable. A large value for AY is favourable, since the yield of hop extract per kg C02 is then high. A low pressure ratio p /p is also favourable, since the mechanical work for compression is then small. Solubility data are however most favourable for extraction when the pressure is high, whilst conditions for separation are most favourable at low pressure. A low initial compressor temperature tt is favourable, since the mechanical work is then small. Too low a temperature, however, requires a refrigeration unit which increases the mechanical work requirement and is thus unfavourable. 

The mechanical work required to move an object an infinitesimal distance d/ against an opposing force F is defined by... 

Obviously lowering the value of y can decrease significantly the mechanical work required for a given cL4. It would be of interest to reduce y as much as possible if the aim is to minimize the siuface work. The question then arises as to how low the interfaeial tension can get. 

Mechanical approach. Consider a soap film supported on a metallic mesh on which a wire is shding (see Figure 20.2). The surface tension, denoted with a Greek letter y(or o), is expressed in N.m or J.m and represents the mechanical work required to increase the film surface area. 

The work term IF is restricted to the mechanical work deflvered to the outside via normal and shear forces acting on the boundary. Electrochemical work, ie, by electrolysis of the fluid, is excluded. Evaluation of the integral requires knowledge of the equation of state and the thermodynamic history of the fluid... 

Unit checkout Check that required mechanical work has been completed, tags and blinds pulled, and temporary piping disconnected. Plant supervision must certify completion of work. Cancel all entry and work permits. Utility system has been commissioned. Check blind list and inspect lines close bleed, drain and sample valves. 

The area contained within the P-V diagram represents the total mechanical work performed by the piston. Some of this work is required to sustain the cycle and must be subtracted from the work calculated tiom the P-V diagram to determine the total external work available from ilie piston. 

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