Assignment Code: MRW-004/TMA/2023

Course Code: MRW-004

Assignment Name: Energy Management

Year: 2023

Verification Status: Verified by Professor

Note:

1. For any question worth 5 marks the word limit is 200 words, for a 10-mark question it is 350 words.

2. All questions are compulsory. All questions carry equal marks.

Q.1 Differentiate between the following:

a) Microscopic and macroscopic approach 5

Ans)

Microscopic approach:

The microscopic approach, also known as the particle approach or the molecular approach, focuses on the behaviour of individual particles that comprise a physical system, such as atoms, molecules, and subatomic particles. Other names for this approach include the atomic approach and the molecular approach. In the study of thermodynamics, statistical mechanics, and quantum mechanics, this method is commonly applied. The behaviour of the system is characterised, according to the microscopic perspective, by the interactions that take place between the various particles. In most cases, mathematical models and equations are used to explain these interactions. Some examples of such models and equations are the Schrodinger equation, which is used in quantum mechanics, and the Maxwell-Boltzmann distribution, which is used in statistical mechanics. The characteristics and actions of these individual particles are then analysed in order to make a prediction about the behaviour of the system as a whole.

Macroscopic approach:

The macroscopic method, often referred to as the continuum approach, places more of an emphasis on the behaviour of the system as a whole than it does on the behaviour of the system's component parts individually. In the study of classical mechanics, fluid dynamics, and thermodynamics, this method is commonly applied. The behaviour of the system is characterised by a collection of macroscopic variables in the macroscopic approach. Some examples of macroscopic variables are temperature, pressure, and density. In the field of thermodynamics, for example, these variables are often measured and studied with the use of mathematical models and equations, such as the Navier-Stokes equations. In the field of fluid dynamics, the laws of thermodynamics are utilised. Following this, a prediction may be made on the behaviour of the system by evaluating the behaviour of these macroscopic variables.

b) Preliminary energy audit and detailed energy audit 5

Ans)

Preliminary energy audit:

An initial energy audit is a fundamental energy evaluation of a building or facility that is carried out with the purpose of locating areas in which there is potential for energy cost reductions. It entails gathering information on topics such as energy use, energy bills, and the energy systems of the building or facility in question. The primary objective of a preliminary energy audit is to locate problem areas where energy is being frittered away and to make suggestions for straightforward, cost-effective steps that can be taken to cut down on overall energy use. In most cases, the report that is produced as a result of an initial energy audit will consist of a list of energy-saving measures, expected savings, and the cost of putting those measures into action.

Detailed energy audit:

An exhaustive investigation of the manner in which a structure or other facility consumes its supply of energy is known as a detailed energy audit. It entails doing an exhaustive investigation of the energy systems present in the building or facility in question, which may include the lighting, heating, ventilation, air conditioning, and process equipment. The thorough energy audit entails the collection of specific data on energy use, energy bills, and the energy systems present in the building or facility being audited. In addition, it is possible that the audit will entail the installation of energy monitoring equipment in order to collect data on the utilisation of energy in real time. The exhaustive investigation of energy use is presented in the report of the detailed energy audit, which also suggests potential areas in which cost reductions might be achieved. The study contains a list of energy-saving measures, as well as an in-depth analysis of the costs associated with their implementation and an estimate of the savings that may be realised as a result.

c) Isochoric and isothermal process 5

Ans)

Isochoric process:

Isochoric processes, also known as constant-volume processes, are types of thermodynamic processes in which the volume of the system does not vary during the process, despite the fact that the pressure and temperature do. This type of process is also known as a constant-volume process. Because there is no change in volume during an isochoric process, the amount of work that is done by or on the system is equal to zero. The equation Q = nCv(T2-T1) can be used to determine the amount of heat transfer that occurs during an isochoric process. In this equation, Q represents the amount of heat transfer, n represents the number of moles of gas, Cv represents the specific heat at constant volume, and T2 and T1 represent, respectively, the final and initial temperatures.

Isothermal process:

The term "isothermal" refers to a type of thermodynamic process in which the temperature of the system stays the same while other variables, such as pressure and volume, shift. Because there is no net change in the amount of energy contained within the system during an isothermal process, the amount of heat that is transferred into or out of the system is proportional to the amount of work that is performed on or by the system. It is possible to determine the amount of heat that is transferred during an isothermal process by solving the equation Q = nRT ln(V2/V1), where Q stands for heat transfer, n stands for the number of moles of gas, R stands for the gas constant, T stands for the temperature, and V2 and V1 stand for the final and initial volumes, respectively.

In a nutshell, a process is said to be isochoric when the volume of the system is maintained at a constant level, whereas a process is said to be isothermal when the temperature of the system is maintained at a constant level. Both of these categories of thermodynamic processes are essential to comprehending and forecasting the behaviour of gases and other forms of thermodynamic systems. Additionally, they are utilised in a broad variety of applications in the fields of physics, chemistry, and engineering.

d) Core type and shell type transformer 5

Ans)

Core type transformer

The windings of a core-type transformer are twisted around an iron core that is located in the middle of the device. Eddy currents can cause significant losses; hence the iron core is often constructed out of thin laminations of high-permeability silicon steel. This helps to mitigate these losses. In most cases, the windings are separated into two distinct coils: one is reserved for the primary winding, while the other is reserved for the secondary winding. In an electrical transformer, the main winding is the one that is linked to the power source, while the secondary winding is the one that is connected to the load. Transformers of the core type are extremely common components in power transmission and distribution networks.

Shell type transformer

Windings are wrapped all the way around a central iron core in a shell-type transformer. This core is separated into two distinct portions that are referred to as the yoke and the limb. The windings are looped around the limb, and the yoke creates a magnetic pathway for the flux to go along. Because of the greater space that exists between the windings in a shell type transformer, this type of transformer has a higher leakage inductance when compared to a core type transformer. This may have an effect on the performance of the transformer. The shell kind of transformer, on the other hand, is favoured in some applications because it allows for the transformer's size and weight to be reduced to the absolute minimum.

Q.2 a) Explain the principle of Energy conservation in details. 5

Ans) The principle of Energy conservation are:

Improving energy efficiency

This comprises employing technology and methods that are energy efficient in order to minimise energy usage while maintaining or enhancing the intended level of service or performance. This might involve making upgrades to appliances that are more energy efficient, enhancing insulation and weatherization, employing lighting that is more energy efficient, and implementing energy-saving techniques in industrial operations.

Energy conservation in transportation

This entails lowering the amount of energy that is consumed in transportation by making use of alternate means of transportation, such as walking, cycling, and public transit; or making use of cars that are more fuel efficient.

Use of renewable energy

This reduces reliance on non-renewable sources of energy such as fossil fuels by shifting toward the use of renewable energy sources to produce electricity and heat. Some examples of renewable energy sources are solar, wind, hydropower, and geothermal energy.

b) Discuss the various barriers to energy conservation. 5

Ans) The various barriers to energy conservation are:

Lack of awareness and understanding

A lack of knowledge and understanding of the benefits of energy conservation as well as the many technologies and practises that are available that are energy efficient is one of the key hurdles that exist in the way of energy conservation. The fact that many individuals are unaware of the financial and environmental benefits of energy conservation might hinder them from taking steps to limit the amount of energy they use since it could cost them money.

High initial costs

The high initial price of energy-efficient devices and practises are another key obstacle to energy conservation. It's possible that the initial purchase price of energy-efficient appliances and equipment is going to be higher, which might discourage people and businesses from making the investment.

Lack of access to capital

It's possible that many people and organisations don't have access to the cash that's needed to invest in energy-efficient practises and technology. This may be especially true for low-income people and small enterprises, both of whom often have a difficult time gaining access to credit at an affordable rate.

Limited availability of energy-efficient products and services

Another obstacle that might stand in the way of energy conservation is the restricted availability of goods and services that are efficient in their use of energy. It's possible that many energy-efficient goods and services aren't easily accessible in some areas, which can slow down the rate at which people adopt them.

Lack of incentives and policies

The absence of financial incentives and government regulations that promote energy efficiency can also be a significant obstacle. Individuals and organisations might not be sufficiently motivated to adopt energy-efficient technology and practises if they are not offered financial incentives such as tax credits, rebates, and grants.

Lack of technical expertise

A lack of technical skills is another obstacle standing in the way of energy saving. It's possible that a lot of people and organisations don't have the technical knowledge and skills needed to put energy-efficient technology and practises into action.

Q.3 Describe the principle of various pressure measuring instruments used in energy audit process. 10

Ans) The principle of various pressure measuring instruments used in energy audit process are:

Bourdon tube pressure gauge

This pressure measuring instrument is used to measure the pressure of fluids and gases. It consists of a flattened, hollow tube that is bent into a circular shape. When the pressure of the fluid or gas is applied to the inside of the tube, it tends to straighten out. This movement is then transmitted to the pointer through a mechanical linkage, and the pressure is displayed on a calibrated dial.

Diaphragm pressure gauge

During the process of conducting an energy audit, a variety of pressure measurement equipment are utilised to measure and monitor the pressure of fluids or gases present in a number of distinct systems. The following is an explanation of the fundamental operating principles behind several typical types of pressure measurement instruments:

Differential pressure gauge

The difference in pressure that exists between two sites in a system may be accurately measured with the help of this pressure measurement equipment. It is constructed of two Bourdon tubes that, in turn, are connected to the system's two points of connection. The disparity in pressure that exists between the two sites results in a disparity in the bending of the two tubes, which is then represented on a dial that has been calibrated appropriately.

Pressure transducer

This device for measuring pressure generates an electrical signal based on the pressure of the fluids or gases it is detecting. It is made up either a piezoelectric element or a diaphragm, both of which are able to deflect in response to variations in pressure. After that, this deflection is transformed into an electrical signal, which may either be seen on a digital readout or sent to a computer or a data logger.

Manometer

When measuring the pressure of fluids and gases contained within a closed system, this pressure measurement equipment is the tool of choice. It is constructed from a tube in the shape of a U that is only half filled with a liquid such as mercury or water. When the fluid or gas pressure is supplied to one end of the tube, it causes the liquid to flow up or down in the tube, depending on where the pressure is applied. After that, the pressure is computed based on the disparity that exists between the heights of the liquid in each of the tube's two branches.

Q.4 a) Proof that energy is the property of the system. 5

Ans) The first rule of thermodynamics, which states that energy cannot be generated or destroyed but can only be changed from one form to another, is a useful tool for gaining an understanding of the idea of energy. According to this law, energy is not a thing or a substance; rather, it is a quality that may be found in systems. The amount of energy that is contained inside a system can either increase or decrease as a result of the processes or changes that it goes through. This shift in energy is mirrored in the system's internal state, which can be characterised by the temperature, pressure, or chemical make-up of the elements involved. The system's energy is said to be conserved, which indicates that the overall quantity of energy contained inside the system does not change.

Take, as an illustration, a system including a steaming mug of coffee and the environment in which it is found. The energy of the system is the total energy of the coffee and its surrounds. This includes the potential energy of the coffee and its surroundings owing to gravity as well as any other types of energy that may be present. The thermal energy of the coffee is included in this total energy as well. If the coffee is allowed to cool down on its own, the total amount of energy in the system will decrease because heat will escape from the coffee and into the surrounding environment. The overall amount of energy in the system is maintained at a steady level because the environment makes up for the energy lost by the coffee. Because energy is a quantifiable amount that is related with the internal state of the system, it may thus be regarded to be a property of the system. Because of this, energy can be considered to be a property of the system. The principle of energy conservation states that the overall quantity of energy in a system must remain unchanged; any changes to the amount of energy must be interpreted as indicating shifts in the system's internal state.

b) Write the statements of second law of thermodynamics and discuss their significance and utility. 5

Ans) The second rule of thermodynamics is a basic concept in physics that regulates the behaviour of energy and entropy in physical systems. This law was developed by James J. Joule in 1848. There are many different formulations of the second law, but the one that follows is among the most widespread:

"Every energy transfer or transformation increases the entropy of the universe."

This is a crucial remark because it suggests that there are limits to the efficiency of the processes involved in the conversion of energy. When one type of energy is converted into another, a portion of that energy will invariably be lost as waste heat. This contributes to a rise in the entropy of both the system and the environment in which it is located. When an automobile engine consumes fuel to create motion, for instance, part of the energy is lost as waste heat that cannot be used to accomplish work. This energy cannot be repurposed. This wasted heat contributes to a rise in the entropy of the engine as well as the environment around it.

Another statement of the second law is:

It is not feasible to build a machine that functions in a cycle and generates no impact other than the transfer of heat from a colder body to a warmer one, as this would be an impossible combination of requirements. It is implied by this assertion, which is referred to as the Kelvin-Planck statement, that it is impossible to develop a perpetual motion machine. A perpetual motion machine is a mechanism that can function without requiring any additional source of energy to do so. Because it would create work without requiring any additional source of energy, such a machine would be in violation of the second rule of thermodynamics. As a result, the entropy of the universe would increase.

Q.5 Describe the various types of powers in an electric circuit with the help of neat diagram. 10

Ans) There are different types of power in an electric circuit, each with its own significance and applications. The main types of power are:

Active Power (P)

The power that is actively used or utilised in a circuit is referred to as active power. The unit of measurement for it is the watt, and other names for it include genuine power and actual power (W). Active power is the power that does the real work in a circuit, such as heating an element or operating a motor, and it is distinguished from passive power by its use of the term "active."

Reactive Power (Q)

Power that is consumed in the process of generating and sustaining electric and magnetic fields inside a circuit is referred to as reactive power. In certain circles, it is referred to as imaginary power, and the unit of measurement for it is volt-amperes reactive (VAR). Although reactive power is essential for the operation of loads that are both inductive and capacitive, it does not directly contribute to the work that the circuit does.

Apparent Power (S)

The combination of active power and reactive power is referred to as apparent power, and it is expressed in terms of volt-amperes (VA). The overall power that is delivered to a circuit is referred to as the circuit's apparent power. This power includes both the useable power and the reactive power that is necessary to run the inductive and capacitive loads.

Instantaneous Power

Power that is either being used up or given off at a certain point in time is referred to as instantaneous power. It is determined by multiplying the instantaneous voltage by the instantaneous current, and it is expressed in terms of watts.

Maximum Power

The term "maximum power" refers to the greatest amount of electrical energy that may be drawn from a given circuit or device when operating under optimal circumstances. In most cases, the maximum power output of a device, such as a solar panel or wind turbine, is what is referred to as the value.

Q.6 Explain the construction and working principle of DC Generator. 10

Ans) A device that can transform mechanical energy into electrical energy is called a direct current (DC) generator, which is also known as a DC dynamo. A direct current (DC) generator consists of a fixed portion known as the stator and a spinning part known as the rotor in its fundamental structure.

A cylindrical frame composed of cast iron or steel serves as the basis for the stator. This frame has a number of holes cut axially around its circumference to create the stator. These holes provide space for the stator winding, which is typically constructed out of copper wire.

A commutator is a cylindrical drum constructed of copper segments that are isolated from one another. This drum is connected to the stator winding, which is wound around it. A number of coils or windings are coiled around an iron core and the rotor is positioned on a shaft so that it may rotate around the shaft. The core is laminated in order to lower the eddy currents, and ball bearings are used in order to install it on the shaft.

When a conductor is moved while being in the presence of a magnetic field, a voltage will be induced in the conductor due to Faraday's law of electromagnetic induction. This law indicates that a voltage will be induced in the conductor. The working concept of a DC generator is based on this law. A voltage is induced in the rotor windings of the generator by rotating the rotor inside the magnetic field of the stator. This voltage is then transmitted to the stator winding through the commutator.

Because of the rotor's constantly shifting location in relation to the stator, the induced voltage in the rotor windings will always point in a different direction as long as the rotor continues to revolve. Alternating current is the term given to electricity that flows in both directions at once (AC). On the other hand, while the rotor revolves, the commutator flips the polarity of the voltage, so converting the alternating current voltage into direct current voltage.

The amount of direct current (DC) voltage that is generated by the generator is related to the speed at which the rotor is rotating, the intensity of the magnetic field, and the number of turns that are present in the stator winding. Any one of these characteristics may be changed to affect how much of a change there is in the voltage that is generated by the generator.

Q.7 Explain the various ways to conserve energy in any industry you have visited recently. 10

Ans) The various ways to conserve energy in any industry you have visited recently are:

Conduct an energy audit:

An energy audit can assist in identifying parts of a building or facility that are squandering energy and pinpointing locations for the installation of energy-saving solutions. An energy audit may be carried out either by a trained energy auditor on the outside or by an internal energy management team on the inside.

Optimize the use of equipment:

The use of energy can be lowered by performing regular equipment maintenance and calibration. For instance, maintaining equipment by keeping it clean and oiled may increase efficiency while simultaneously lowering energy use.

Use energy-efficient lighting:

It is possible to save a large amount of electricity by switching out typical light fixtures for ones that are more energy efficient. LED lights having a longer lifespan than typical incandescent bulbs, in addition to being more energy-efficient than the latter.

Improve insulation:

It is possible to limit heat loss or gain by proper insulation of walls, roofs, and windows, which in turn reduces the demand for heating and cooling. Insulation, windows with multiple panes, and several other approaches are all viable options for accomplishing this goal.

Use renewable energy sources:

In order to reduce reliance on fossil fuels, renewable energy sources such as sun, wind, and geothermal can be utilised to provide power or heat.

Implement energy management systems:

The implementation of an energy management system may assist in the monitoring and control of energy consumption, as well as the identification of possibilities for energy conservation and the tracking of energy savings.

Encourage employee involvement:

It is possible to achieve large energy savings by providing incentives to staff to improve their energy efficiency. This can be accomplished through several means, including workout programmes, competitions to save energy, and other activities.

Use energy-efficient motors and drives:

Motors and drives that are more efficient with energy can cut energy usage by a substantial amount. The usage of variable speed drives allows for a reduction in the amount of energy that is consumed by motors that are operating at less than their maximum capacity.

Q.8 Write short notes on the following :

a) Non cyclic power plants 5

Ans) Power plants that generate electricity without the utilisation of steam cycles are referred to as on-cyclic power plants. They are often put to use in regions that do not have access to a reliable supply of water, which is necessary for the creation of steam. In order to produce electricity, non-cyclic power plants will often employ the utilisation of a gas turbine or a reciprocating engine. Plants using gas turbines to generate electricity.

Fuel is burned in a gas turbine, which then converts the chemical energy of the fuel into usable mechanical energy. The gas turbine is basically a big jet engine that utilises compressed air and fuel to create a high-temperature, high-pressure gas that spins a turbine. This gas is produced by combining the two ingredients in a high-pressure chamber.

A generator is coupled to the turbine so that it may convert the kinetic energy produced by the turbine into electrical energy. During times of high demand, the output of other power plants may be supplemented by the electricity generated by gas turbine plants, which are often employed to supply peaking power. Power plants that employ revolving engines to generate electricity transfer the chemical energy stored in fuel into the usable form of mechanical energy using internal combustion engines. In most cases, natural gas, diesel, or some other type of liquid or gaseous fuel is used to power the engines.

b) Combustion analyzer 5

Ans) A device known as a combustion analyzer is one that is employed for the purpose of determining the relative amounts of several gases produced by a combustion process. Monitoring and improving the efficiency of the combustion process in furnaces, boilers, and other combustion-based systems is a typical application of this technology in the energy business.

The analyzer typically consists of a probe that is inserted into the combustion chamber or flue, a sensor that measures the concentration of gases in the sample, and a display or readout that provides real-time data on the composition of the flue gases. All of these components work together to determine the composition of the flue gases. The sensor will often utilise infrared, electrochemical, or other detection methods in order to determine the concentration of gases such as oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), and sulphur dioxide (SO2) (SO2).

c) Switch gear 5

Ans) The term "switchgear" refers to a variety of different pieces of electrical equipment that are used to regulate, protect, and isolate other pieces of electrical equipment and circuitry. Switches, circuit breakers, fuses, relays, and disconnectors are all examples of the types of devices that fall under this category. This category is utilised often in industrial, commercial, and utility power systems.

Switchgear's primary job is to prevent overloads, short circuits, and other types of malfunctions from causing harm to the electrical equipment and circuits they are responsible for protecting. It also enables the operation of electrical equipment to be carried out in a manner that is secure and dependable by providing a way by which the equipment may be disconnected from the power source so that it can be maintained or repaired.

Switchgear is frequently categorised according to the voltage level it operates at, such as low voltage (LV), medium voltage (MV), or high voltage (HV). Switchgear is generally located in an electrical switchroom or substation (HV).

Another way to categorise it is according to the type of switchgear it is, which can be either metal-enclosed switchgear, air-insulated switchgear, gas-insulated switchgear, or hybrid switchgear.

d) Evaporative cooling 5

Ans) Evaporative cooling is a natural method of cooling that makes use of the evaporation of water in order to bring the temperature of the air around it down.

The technique works by passing hot air through a wet medium, such a wet pad or filter, which causes the water to evaporate and pick up heat from the surrounding air as it does so. The cooled air is then pumped back into the area, generating a natural and effective cooling effect.

The key components of an evaporative cooling system include:

Wet media

A material that is used to store water and generate a wide surface area for evaporation to take place, such as a wet pad or filter, is an example of this type of material.

Water supply

Either a pump or a system that relies on gravity to deliver the water to the wet medium is typically used.

Air supply

Warm air is drawn through wet material with the help of a fan or blower, which ultimately results in the water evaporating and the air becoming cooler.

Exhaust

Air that has been cooled is brought back into the area, while air that is warm and humid is vented to the outside of the building.