Potential for heat

The output from the turbine might be superheated or partially condensed, as is the case in Fig. 6.32. If the exhaust steam is to be used for process heating, ideally it should be close to saturated conditions. If the exhaust steam is significantly superheated, it can be desuperheated by direct injection of boiler feedwater, which vaporizes and cools the steam. However, if saturated steam is fed to a steam main, with significant potential for heat losses from the main, then it is desirable to retain some superheat rather than desuperheat the steam to saturated conditions. If saturated steam is fed to the main, then heat losses will cause excessive condensation in the main, which is not desirable. On the other hand, if the exhaust steam from the turbine is partially condensed, the condensate is separated and the steam used for heating. 

Appropriate medical considerations, such as limitations during temperature extremes and potential for heat stress [OSHA Reference, 120(x)]... 

Does the site safety and health officer have the authority to downgrade the required level of PPE, when it is safe to do so, to reduce the potential for heat stress ... 

Does the potential for heat stress appear to have been considered in the selection of PPE ... 

The rate dependence of fatigue strength demands careful consideration of the potential for heat buildup in both the fatigue test and in service. Generally, since the buildup is a function of the viscous component of the material, the materials that tend toward... 

Figure 23.43 Adding a new steam main at the site pinch (for a pinched site) increases the potential for heat recovery through the steam system.

In summary, it follows that temperature may be viewed as a potential for heat flux, pressure as a potential for volume change and p as a chemical potential for matter flow. 

The area bound between the saturation line and the operating line is proportional to the potential for heat transfer. We now have two choices on how to obtain the final solution (Ntu ) a graphical or numerical solution. Each is outlined below ... 

The design of cooling systems that automatically incorporate ion-exchangers to produce a fully softened makeup water is generally not to be recommended, whether it is specified to minimize risks of legionellosis, or the potential for heat-exchanger scaling, or for any other reason, as it may create more problems than it solves. 

In this case, the perpendicular distances are strictly less than HRAT, and as TIAT decreases the demarcation lines originating at hot stream inlets rotate upward toward the horizontal (see for instance point B, B", B " in Figure 8.24). The consequences of this rotation are that the horizontal components increase, which reflects an increase in the residual heat flow in each interval as well as the potential for heat flow across the pinch. 

To identify blocked oudet scenarios, all maximum pressures of all inlet sources were compared to maximum allowable working pressure (MAWP) of the equipment under consideration. In addition, the potential for heat input from the process to result in vaporization at MAWP was considered. 

There is poor air circulation in shipping containers therefore, there is a potential for heat and fume buildup that makes it hazardous when working inside it. All drums must be inspected for leaks or bulging as they are being unloaded. 

The successful operation of this system demonstrated the potential for heat recovery from incineration of cotton gin trash. At a 30% recovery ratio, enough heat can be recovered from the incineration process to supply most of the energy required for seed cotton drying, even in low-capacity gins (Table IX). Only the size and volume of the ginning operation will dictate whether such recovery will be economically feasible. 

Table IX. Potential for Heat Recovery from Incineration of Gin Trash.

The potential for heat-induced illness is also likely to be highest for handlers on foot. Not only are they often exposed to direct, unshaded sunlight, they are also often carrying, pushing, pulling, or otherwise manipulating equipment or pesticide containers. 

Agricultural pesticide handlers use some pesticides in enclosed areas such as greenhouses, silos, and bams. The use of pesticides in such areas increases the risk of inhalation exposure and may require the use of a respiratory protection device even if the identical application outdoors would not warrant such protection. The likelihood of increased potential for heat stress due to the enclosure is dependent on the effectiveness of the ventilation system. 

On the basis of the selected PPE, adjust the work regimen to take into account reduced productivity associated with the PPE, the potential for heat stress, and the possibility that the available PPE may not fully meet all the protection requirements. 

Level of protection is that combination of gloves, boots, garment, goggles, etc., that is necessary to provide protection from the potential hazard. The goal is always to use the minimum level of PPE that is necessary. By so doing, costs, effect on productivity, and potential for heat stress are minimized, and the likelihood for worker acceptance (comphance) is increased. 

The potential for heat stress is influenced by many factors, including ambient temperature, relative humidity, amount of sunshine, wind speed, amount and type of PPE, and the workload. 

Unfortunately, PPE used for protection from pesticides can increase the potential for heat stress. The PPE features that keep pesticides out also serve to prevent body heat from escaping. People cannot work as long or as hard when the PPE they are wearing reduces the body s ability to maintain its thermal balance. Under some enviromnental conditions, certain activities cannot be performed withont jeopardizing the health of the worker unless auxiliary cooling is provided. The risk that PPE may aggravate heat stress must be balanced with the PPE s potential worker protection benefits. 

As mentioned above, heat transfer will occur whenever there exists a temperature difference in a medium. Similarly, whenever there exists a difference in the concentration or density of some chemical species in a mixture, mass transfer must occur. Hence, just as a temperature gradient constitutes the driving potential for heat transfer, the existence of a concentration gradient for some species in a mixture provides the driving potential for transport of that species. Therefore,... 

Analyze potential for heat recovery from fuel cell/hydrogen production systems... 

However, the only heat potential of much interest is the enthalpy, and in fact we could say that the only practical Interest in the enthalpy is that it is a potential for heat in constant pressure processes. As before, if the only work is PAY in a constant pressure process (and remember that at constant P, work is exactly equal to —PAY, not < -PAY), then... 

We should emphasize that strictly speaking, U, A, H, and G should be spoken of in each case as reversible work potentials, rather than as work potentials, since it is only in the reversible case that the work is equal to the change in the potential, analogous to (5.17). Note though, that H is a potential for heat in isobaric processes, reversible or not. 

---