Section Five. ENVIRONMENTAL PROTECTION AGAINST ENERGY IMPACT
CHAPTER 18 PRINCIPLES AND METHODS OF PROTECTION AGAINST ENERGY IMPACT
Harmful energy impacts generated by technical systems form dangerous zones in the living space of the technosphere, where the ratio There are only zones of activity and stay of a person with dangerous zones in the living space: in the conditions of production - this is the working area, the workplace, in the home - the zone of housing, urban environment.
By varying the mutual arrangement of dangerous zones and zones of human presence in space, it is possible to significantly influence the solution of tasks to protect people and the environment from negative energy impacts.
The radical way to ensure security is to protect by distance - a variant of the mutual arrangement of the zones of stay and the action of negative energy factors by diluting dangerous zones and human zones in space. Distance protection is realized by remote control, observation and stay. Dangerous zones and zones of human presence can be developed not only in space, but also in time, realizing the alternation of the periods of action of hazards and periods of observation of the state of technical systems.
Unfortunately, distance protection is not always possible in practice. To ensure human security in these cases, use:
improvement of dangerous energy sources in order to minimize the risks they generate, which not only reduces the level of danger, but also reduces the size of the danger zone;
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Fig. 18.1. Variants of using eco-bio-protective techniques for reducing harmful energy impacts: 1 - devices that are part of the source of impacts; 2 - devices installed between the source and the activity area; 3 - devices for protecting the area of activity; 4- means of individual protection of a person; ΒΦ is a harmful factor
the introduction of protective equipment (eco-bio-protective technology) to isolate the human zone from negative impacts;
the use of personal protective equipment against hazards.
In order to limit the harmful effect on human and habitat, the technical energy system requires requirements on the amount of energy pollution in the form of maximum permissible emissions to the habitat. Limit values of radiation are found, based on the maximum permissible levels (PDU) of the effect of energy pollution and the distance between the radiation source and the zone of human presence.
If the improvement of technical systems does not manage to provide maximum permissible effects on a person in the area of his stay, then it is necessary to use ecobio protective equipment in the form of various energy-absorbing fences, shields, protective boxes (Figure 18.1).
In cases where the possibilities of eco-bio-protective equipment for collective use are limited and do not provide the values of remote control in the areas of people's stay, they are protected by personal protective equipment.
When solving the protection tasks, the source, the energy receiver and the protective device are selected (Figure 18.2), which reduces the energy flow to the receiver to allowable levels.
The protective device (RAM) has the ability to reflect, absorb, be transparent with respect to the energy flow. From the total energy flow of W + to the memory, part A a is absorbed, part W - reflected and part W ~ - passes through the memory.
P and c. 18.2. Energy balance of a protective device (memory)
Then the memory can be characterized by the following energy coefficients: the absorption coefficient α = Wa/W +, the reflection coefficient ρ = W-/W +, the transmission coefficient τ = W-/W +.
In this case, the equality
The sum α + τ = 1 - ρ = ν (where ν = W v /W +) characterizes the unrefined energy flow W v that has passed to the memory.
If α = 1, then the charger absorbs all the energy coming from the source; for p = 1, the memory has a 100% reflectivity, and the equality τ = 1 means the absolute transparency of the memory, that is, the energy passes through the device without loss.
Principles of protection:
1) the protection is carried out due to the reflectivity of the memory device, ρ → 1;
2) protection is carried out due to the absorptive capacity of memory, α → 1;
3) protection taking into account the transparency properties of the memory, τ → 1.
In practice, the principles are combined, obtaining various methods of protection. The most widely used methods of protection by insulation and absorption.
Isolation methods are used when the source and the energy receiver, which is simultaneously the object of protection, are located on different sides of the memory (Figure 18.3).
At the heart of these methods is the decrease in the transparency of the medium between the source and the receiver, i.e., the fulfillment of the condition τ → 0. Two basic methods of isolation can be distinguished: a method in which the decrease in the transparency of the medium is achieved by absorbing the energy of the SU, ie, the condition τ → 0 is ensured by the condition α → 1 (see Figure 18.3, a), and a method in which the decrease in the transparency of the medium is achieved due to the high reflectance of the memory, i.e., the condition τ → 0 is ensured by the condition p → 1 (see Figure 18.3, b).
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P and c. 18.3. Methods of isolation when the source (I) and the receiver (P) are located from different sides of the protective device (RAM): a - the energy is absorbed; b - the energy is reflected
Fig. 18.4. Absorption methods when the source (И) and the receiver (П) are located on one side of the protective device (ZУ): а - energy is selected; b - energy is skipped
The absorption principle is based on the principle of increasing the energy flux that has passed through the memory (Figure 18.4), i.e., the achievement of the condition ν. There are two types of absorption of energy: the absorption of energy by the memory itself due to its selection from the source in one or another form, including in the form of irreversible losses, which is characterized by the coefficient α (see Figure 18.4, a), and the energy absorption due to the large transparency of the memory, which is characterized by the coefficient τ (see Figure 18.4, b).
Since ρ → 0 as ν → 1, the absorption methods are used to reduce the reflected energy flux; the source and the energy receiver are usually located on one side of the memory.
When considering the propagation of oscillations, along with the coefficient α, the loss coefficient η is used, which characterizes the amount of energy of the scattered memory:
where W s and E s are the average power for the oscillation period T and the energy dissipated for the same time; w = 2к/Т - the circular frequency; ε is the energy stored by the system.
Qualitative assessment of the degree of implementation of the objectives of protection can be carried out in two ways:
1) determine the protection factor K w as a ratio
2) determine the protection factor as a ratio
The effectiveness of protection (dB) is estimated by the ratio
The choice of methods to protect against energy impacts depends on the type and form of manifestation of energy. In the protection against mechanical and acoustic vibrations, the main methods for reducing their level of influence are the reduction of the energy parameters in the source, the optimal orientation of the source of oscillations relative to the object of action, the absorption of a part of the generated oscillation energy, the decrease in the vibration energy along the path of their propagation from the source by isolation, shielding and damping, protection by distance and time, carrying out organizational, technical and social-rehabilitation measures.
Protection from vibration in industry and the environment is effected by the source of vibration by reducing vibration along the way of its spread, by using the appropriate labor organization, using personal protective equipment, by carrying out medical and preventive measures.
Among the methods of protection against EMF and ionizing radiation in the environment is protection by distance, screening, partial absorption of radiation power, reducing the level of energy impact by scattering and diverting part of the energy from the place of its localization into the environment. The main engineering measures include the reduction of the radiation power directly in the source and electromagnetic shielding.
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