State first law of thermodynamics for (i) closed system and cyclic process (ii) closed system and non-cyclic process

State first law of thermodynamics for (i) closed system and cyclic process (ii) closed system and non-cyclic process
by

1 Answer

Answer :

First Law of Thermodynamics: 

i) Closed System Cyclic Process :- It states that if a system executes a cycle, transferring work and heat through its boundary, the net heat transfer is equivalent to the network transfer and does not place any restriction on the direction of flow but the reversal of the process not violet the first law. According to this statement of first law the potential energy can be converted into kinetic energy and kinetic energy can be converted into potential energy but in natural practice this does not happen. 

ii) Closed system Non cyclic process:- The principle of conservation of energy leads to first law of thermodynamics. This principle states that „energy can neither be created nor be destroyed though it can be transformed from one form to another form of energy. According to this law, when a system undergoes a change of state (thermodynamic process) both heat and work transfer takes place. The net energy transfer is stored within the system and is known as stored energy or total energy of system. 

 Q = ΔU + W
by

Related questions

In a boiler enthalpy of water supplied was 2000 kJ/kg. Enthalpy being added by fuel combustion is 3200 kJ/kg. Using first law of thermodynamics, find amount of heat supplied if steam generation rate is 10 tons per hour.

Description : In a boiler enthalpy of water supplied was 2000 kJ/kg. Enthalpy being added by fuel combustion is 3200 kJ/kg. Using first law of thermodynamics, find amount of heat supplied if steam generation rate is 10 tons per hour.

Last Answer : Heat supplied Q = m (h2-h1) …….(Steady flow energy equation for boiler) ; h2=3200 KJ/kg h1=2000 KJ/kg m = 10 Tons /hour = (10 x 1000)/3600 kg/sec = 2.77 Kg/sec Q = 2.77(3200-2000) = 3324 KJ/sec heat supplied for 10 Tons/hr steam generation

Second law of thermodynamics is concerned with the (A) Amount of energy transferred (B) Direction of energy transfer (C) Irreversible processes only (D) Non-cyclic processes only

Description : Second law of thermodynamics is concerned with the (A) Amount of energy transferred (B) Direction of energy transfer (C) Irreversible processes only (D) Non-cyclic processes only

Last Answer : (B) Direction of energy transfer

State Fourier's law of 'conduction and Stefan Boltzmann law of radiation. Express mathematically.

Description : State Fourier's law of 'conduction and Stefan Boltzmann law of radiation. Express mathematically.

Last Answer : Fourier law of heat conduction- It state that for homogeneous material, the rate heat transfer in steady state in any direction is linearly proportional to temperature gradient in that direction. Q α dt/ ... proportional to fourth power of absolute temperature of the body. E α T4 E= σT4

Explain Dalton's law in respect to steam condensers.

Description : Explain Dalton's law in respect to steam condensers.

Last Answer : It states that' The pressure exerted by mixture of air and steam is equal to sum of partial pressures, which each constitute would exert, if it occupies the same volume . Mathematically, Pc ... mixture of air and steam Pa = Partial pressure of air Ps = Partial pressure of steam

An engine is supplied with 4 kW of heat energy. It is found that it produce 4 kW of work. Which kind of perpetual machine it is? Which law is violated? Also describe other kind of perpetual machine you know.

Description : An engine is supplied with 4 kW of heat energy. It is found that it produce 4 kW of work. Which kind of perpetual machine it is? Which law is violated? Also describe other kind of perpetual machine you know.

Last Answer : PMM-II: A heat engine which violates Kelvin plank statement of the second law of thermodynamics is known as Perpetual Motion Machine of the second kind (PMM-II). Or 100 percent efficient machine which is ... no machine can produce energy of its own without consuming any other form of energy.

(i)State why heat changes in physical and chemical processes are indicated by enthalpy changes and not by entropy changes? (ii)What are the limitations of First Law of thermodynamics?

Description : (i)State why heat changes in physical and chemical processes are indicated by enthalpy changes and not by entropy changes? (ii)What are the limitations of First Law of thermodynamics?

Last Answer : (i) Most of the processes are carried out in an open system i.e, at constant pressure. (ii)(a) Can’t explain the feasibility of the reaction. (b)It poses no restriction on the direction of flow of heat. (c)Practically it is not possible to convert the heat energy into an equivalent amount of work.

Differentiate induced draft and forced draft cooling towers based on (i) Location of fan (ii) Corrosion of blades (iii) Efficiency (iv) Fan size

Description : Differentiate induced draft and forced draft cooling towers based on (i) Location of fan (ii) Corrosion of blades (iii) Efficiency (iv) Fan size

Last Answer : Differentiate induced draft and forced draft cooling towers based on (i) Location of fan (ii) Corrosion of blades (iii) Efficiency (iv) Fan size

In surface condensers write role of (i) Water tubes (ii) Shell (iii) Baffle plate (iv) Tube sheet

Description : In surface condensers write role of (i) Water tubes (ii) Shell (iii) Baffle plate (iv) Tube sheet

Last Answer : Function of parts in surface condensers 1. Water tubes- Cooling water flows through it , for convective heat transfer to occur with steam outside the tubes 2. Shell- Outer body, all components are ... and improves heat transfer 4. Tube sheet- All tubes are supported at the end in tube sheet

Ammonia is (a) non-toxic (b) non-inflammable (c) toxic and non-inflammable (d) highly toxic and inflammable

Description : Ammonia is (a) non-toxic (b) non-inflammable (c) toxic and non-inflammable (d) highly toxic and inflammable

Last Answer : Ans: d

Freon group of refrigerants are (a) inflammable (d) toxic (c) non-toxic and non-inflammable (d) non-toxic and inflammable

Description : Freon group of refrigerants are (a) inflammable (d) toxic (c) non-toxic and non-inflammable (d) non-toxic and inflammable

Last Answer : Ans: c

The condensing pressure due to the presence of non-condensable gases, as compared to that actually required forcondensing temperatures without non-condensable gases, (a) will be higher (b) will be lower (c) will remain unaffected (d) may be higher or lower depending upon the nature of non-condensable gases

Description : The condensing pressure due to the presence of non-condensable gases, as compared to that actually required forcondensing temperatures without non-condensable gases, (a) will be higher (b) will be ... remain unaffected (d) may be higher or lower depending upon the nature of non-condensable gases

Last Answer : Ans: a

On psychrometric chart, wet bulb temperature lines are A. horizontal with uniformly spaced B. horizontal with non-uniformly spaced C. inclined with uniformly spaced D. inclined with non-uniformly spaced

Description : On psychrometric chart, wet bulb temperature lines are A. horizontal with uniformly spaced B. horizontal with non-uniformly spaced C. inclined with uniformly spaced D. inclined with non-uniformly spaced

Last Answer : ANSWER :C

According to first law of thermodynamics  (a) work done by a system is equal to heat transferred by the system  (b) total internal energy of a system during a process remains constant  (c) internal energy, enthalpy and entropy during a process remain constant  (d) total energy of a system remains constant

Description : According to first law of thermodynamics  (a) work done by a system is equal to heat transferred by the system  (b) total internal energy of a system during a process remains constant  ( ... , enthalpy and entropy during a process remain constant  (d) total energy of a system remains constant

Last Answer : Answer : d

The second law of thermodynamics states that (A) The energy change of a system undergoing any reversible process is zero (B) It is not possible to transfer heat from a lower temperature to a higher temperature (C) The total energy of system and surrounding remains the same (D) None of the above

Description : The second law of thermodynamics states that (A) The energy change of a system undergoing any reversible process is zero (B) It is not possible to transfer heat from a lower temperature to a higher temperature (C) The total energy of system and surrounding remains the same (D) None of the above

Last Answer : (D) None of the above

“The entropy change of a system during a process is equal to the net entropy transfer through the system boundary and the entropy generated within the system”. This statement is known as:  A. Entropy generation  B. Entropy change of a system  C. Entropy balance relation  D. Third law of thermodynamics

Description : The entropy change of a system during a process is equal to the net entropy transfer through the system boundary and the entropy generated within the system . This statement is known as:  A. Entropy ...  B. Entropy change of a system  C. Entropy balance relation  D. Third law of thermodynamics

Last Answer : Entropy balance relation

What states that the net change in the total energy of the system during a process is equal to the difference between the total energy entering and the total energy leaving the system during that process?  A. Third law of thermodynamics  B. Conservation of energy principle  C. Second law of thermodynamics  D. Conservation of mass principle

Description : What states that the net change in the total energy of the system during a process is equal to the difference between the total energy entering and the total energy leaving the system during ... Conservation of energy principle  C. Second law of thermodynamics  D. Conservation of mass principle

Last Answer : Conservation of energy principle

What states that the net mass transfer to or from a system during a process is equal to the net change in the total mass of the system during that process?  A. Third law of thermodynamics  B. Conservation of energy principle  C. Second law of thermodynamic  D. Conservation of mass principle

Description : What states that the net mass transfer to or from a system during a process is equal to the net change in the total mass of the system during that process?  A. Third law of thermodynamics  B. Conservation of energy principle  C. Second law of thermodynamic  D. Conservation of mass principle

Last Answer : Conservation of mass principle

Zeroth law of thermodynamics  (a) deals with conversion of mass and energy  (b) deals with reversibility and irreversibility of process  (c) states that if two systems are both in equilibrium with a third system, they are in thermal equilibrium with each other  (d) deals with heat engines  (e) does not exist.

Description : Zeroth law of thermodynamics  (a) deals with conversion of mass and energy  (b) deals with reversibility and irreversibility of process  (c) states that if two systems are both in equilibrium with a ... in thermal equilibrium with each other  (d) deals with heat engines  (e) does not exist.

Last Answer : Answer : c

In sensible cooling process the relative humidity: A. decreases B. increases C. remains constant D. none of the above

Description : In sensible cooling process the relative humidity: A. decreases B. increases C. remains constant D. none of the above

Last Answer : ANSWER : B

Humidification is the process of addition moisture in air at A. constant wet bulb temperature B. constant dry bulb temperature C. constant latent heat D. none of the above

Description : Humidification is the process of addition moisture in air at A. constant wet bulb temperature B. constant dry bulb temperature C. constant latent heat D. none of the above

Last Answer : ANSWER : B

When, H1 = Total heat of air entering the coil (heating or cooling) H2 = Total heat of air leaving the coil (heating or cooling) H3 = Total heat of air at the end of the process (humidification or dehumidification) then, the sensible heat factor (H2 – H1) / (H3 – H1) represents the process of A. cooling and humidification B. cooling and dehumidification C. heating and humidification D. heating and dehumidification

Description : When, H1 = Total heat of air entering the coil (heating or cooling) H2 = Total heat of air leaving the coil (heating or cooling) H3 = Total heat of air at the end of ... A. cooling and humidification B. cooling and dehumidification C. heating and humidification D. heating and dehumidification

Last Answer : ANSWER : C

Which of the following statement is true? A. the chart is plotted for pressure equal to 760mm Hg B. the constant wbt line represents adiabatic saturation process C. the constant wbt line coincides with constant enthalpy line D. all of the mentioned

Description : Which of the following statement is true? A. the chart is plotted for pressure equal to 760mm Hg B. the constant wbt line represents adiabatic saturation process C. the constant wbt line coincides with constant enthalpy line D. all of the mentioned

Last Answer : ANSWER : D

The process of breaking up or liquid into fine droplets by spraying is A. vaporization B. atomization C. condensation D. evaporation

Description : The process of breaking up or liquid into fine droplets by spraying is A. vaporization B. atomization C. condensation D. evaporation

Last Answer : ANSWER : B

In a single stage reciprocating air compressor, the work done on air to compressor is from suction pressure to delivery pressure will be minimum when the compression is A. Isothermal process B. Adiabatic process C. Polytropic process D. Constant pressure process.

Description : In a single stage reciprocating air compressor, the work done on air to compressor is from suction pressure to delivery pressure will be minimum when the compression is A. Isothermal process B. Adiabatic process C. Polytropic process D. Constant pressure process.

Last Answer : ANSWER : A

For minimum work input in a two stage compression process the intermediated pressure is the A. Arithmetic process of suction and discharge pressure B. Logarithmic mean of suction and discharge pressure C. Geometric mean of suction and discharge pressure D. Hyperbolic mean of suction and discharge

Description : For minimum work input in a two stage compression process the intermediated pressure is the A. Arithmetic process of suction and discharge pressure B. Logarithmic mean of suction and discharge pressure C. Geometric mean of suction and discharge pressure D. Hyperbolic mean of suction and discharge

Last Answer : ANSWER : C

The process of breaking up a liquid into fine droplets by spraying is called a. vaporization b. carburetion c. injection d. atomization

Description : The process of breaking up a liquid into fine droplets by spraying is called a. vaporization b. carburetion c. injection d. atomization

Last Answer : ANSWER d. atomization

Supercharging is the process of a. supplying the engine with air at a density greater than the density of the surrounding atmosphere b. providing forced cooling air c. injecting excess fuel d. raising the exhaust pressure

Description : Supercharging is the process of a. supplying the engine with air at a density greater than the density of the surrounding atmosphere b. providing forced cooling air c. injecting excess fuel d. raising the exhaust pressure

Last Answer : ANSWER a. supplying the engine with air at a density greater than the density of the surrounding atmosphere

Represent constant volume process on PV & TS diagram for steam.

Description : Represent constant volume process on PV & TS diagram for steam.

Last Answer : Represent constant volume process on PV & TS diagram for steam.

In a constant pressure process steam is generated from 10 bar and 0.8 dry condition till it become dry and saturated. Determine amount of heat added per kg of steam. From steam table at 10 bar Tsat = 179.9°C hf = 762.6 kl/kg, hg = 2776.2 kJ/kg

Description : In a constant pressure process steam is generated from 10 bar and 0.8 dry condition till it become dry and saturated. Determine amount of heat added per kg of steam. From steam table at 10 bar Tsat = 179.9°C hf = 762.6 kl/kg, hg = 2776.2 kJ/kg 

Last Answer : Constant pressure process Final condition of steam is dry saturated Enthalpy of dry steam = hg= hf + hfg =2776.2 KJ/Kg .Given Latent heat of vaporization = hfg = hg - hf =2776.2-762.6 =2013.6 KJ/Kg Initial condition ... hfg = 762.6+0.8 X 2013.6 =2373.48 KJ/Kg Heat added = hg-hw = 402.72 KJ/kg

A gas is compressed from 1 bar and 30°C to 5 bars and 30°C. Identify process and show on PV diagram.

Description : A gas is compressed from 1 bar and 30°C to 5 bars and 30°C. Identify process and show on PV diagram.

Last Answer : Gas is compressed from (1) 1 bar 30 0C to (2) 5 bar 30 0C Temp is constant. Hence process is isothermal. P x V = Constant

_________ law of thermodynamics ascertains the direction of a particular spontaneous process. (A) Zeroth (B) First (C) Second (D) Third

Description : _________ law of thermodynamics ascertains the direction of a particular spontaneous process. (A) Zeroth (B) First (C) Second (D) Third

Last Answer : (C) Second

During light reaction of photosynthesis, which of the following phenomenon is observed during cyclic phosphorylation as well as non-cyclic phosphorylation? (a) Release of O2 (b) Formation of ATP (c) Formation of NADPH (d) Involvement of PS I and PS II pigment systems

Description : During light reaction of photosynthesis, which of the following phenomenon is observed during cyclic phosphorylation as well as non-cyclic phosphorylation? (a) Release of O2 (b) Formation of ATP (c) Formation of NADPH (d) Involvement of PS I and PS II pigment systems

Last Answer : (b) Formation of ATP

The horizontal line in psychrometric chart joining the change of state of air represents A. humidification B. sensible cooling or heating C. sensible cooling or heating with humidification D. sensible cooling or heating with dehumidification

Description : The horizontal line in psychrometric chart joining the change of state of air represents A. humidification B. sensible cooling or heating C. sensible cooling or heating with humidification D. sensible cooling or heating with dehumidification

Last Answer : ANSWER : B

State necessity of super heater in steam boilers. State advantages of economizer.

Description : State necessity of super heater in steam boilers. State advantages of economizer. 

Last Answer : Necessity of super heater in steam boilers: 1. The efficiency of the boiler is increase with the use of superheated steam. 2. It eliminates the erosion of the turbine blades. 3. It reduces ... water. 5. This unit improves the overall efficiency of the boiler by reducing the fuel consumption. 

Describe only construction and working of pipe in pipe heat exchanger. State it’s two applications.

Description : Describe only construction and working of pipe in pipe heat exchanger. State it’s two applications.

Last Answer : Pipe Heat Exchanger: Construction and Working : In Pipe heat exchanger design, an important factor is the type of flow pattern in the heat exchanger. A pipe heat exchanger will ... more compact. Application : Oil refinery industries , Waste water management, Refrigeration system  

State regulations for boilers which fall under IBR boiler

Description : State regulations for boilers which fall under IBR boiler

Last Answer : Boiler Regulations : 1. A boiler cannot be put to use unless it has been registered with the Chief Inspector of Boilers. 2. The maximum working pressure of the boiler has to be ... Accident inspection, Casual inspection 8. Violation of law is liable to prosecution and punishment with fine.

State two similarities and two dissimilarities between heat and work.

Description : State two similarities and two dissimilarities between heat and work.

Last Answer : Heat and work Similarities- Both are not properties of system, both are boundary phenomena, both are path functions, both are form of energy Dissimilarities-Work is high grade energy, heat is low ... but entire work can be converted into heat ; System can possess heat, but it never possess work

Write continuity equation for nozzles. State involved with their units. meaning of all terms

Description : Write continuity equation for nozzles. State involved with their units. meaning of all terms 

Last Answer : Continuity equation for nozzle Mass flow rate = Density x Area x Velocity ( Density = 1/v) m = (AC/v ) = A1C1/v1) = (A2C2/v2) where, m = mass flow rate of steam in kg/s A= cross ... given section in m2 v = specific volume of steam at given section in m3/kg C= velocity of steam in m/s

State two factors on which efficiency of cooling tower depends.

Description : State two factors on which efficiency of cooling tower depends.

Last Answer : Efficiency of cooling tower depends on 1.Losses in duct, piping and joints, pipes should be free from scale/rust 2.Efficient heat transfer, maintenance of piping , Ensure fill is clean and free of debris. 3.Sufficient airflow and correct fan speed. 

The formation of frost on cooling coils in a refrigerator (a) increases heat transfer (b) improves C.O.P. of the system (c) increases power consumption (d) reduces power consumption

Description : The formation of frost on cooling coils in a refrigerator (a) increases heat transfer (b) improves C.O.P. of the system (c) increases power consumption (d) reduces power consumption

Last Answer : Ans: c

The condition of refrigerant before entering the expansion or throttle valve, in a vapour compression system (a) dry vapour (b) wet vapour (c)liquid-vapour mixture (d) high pressure saturated liquid

Description : The condition of refrigerant before entering the expansion or throttle valve, in a vapour compression system (a) dry vapour (b) wet vapour (c)liquid-vapour mixture (d) high pressure saturated liquid

Last Answer : Ans: d

The general rule for rating refrigeration systems (excepting for CO2 system) is to approximate following h.p. per ton of Refrigeration (a) 0.1 to 0.5 h.p. per ton of refrigeration (b) 0.5 to 0.8 h.p. per ton of refrigeration (c) 1 to 2 h.p. per ton of refrigeration (d) 2 to 5 h.p. per ton of refrigeration

Description : The general rule for rating refrigeration systems (excepting for CO2 system) is to approximate following h.p. per ton of Refrigeration (a) 0.1 to 0.5 h.p. per ton of refrigeration (b) 0.5 to 0.8 h.p. per ... (c) 1 to 2 h.p. per ton of refrigeration (d) 2 to 5 h.p. per ton of refrigeration

Last Answer : Ans: c

Most of the domestic refrigerators work on the following refrigeration system (a) vapour compression (b) vapour absorption (c) carnot cycle (d) electrolux refrigerator

Description : Most of the domestic refrigerators work on the following refrigeration system (a) vapour compression (b) vapour absorption (c) carnot cycle (d) electrolux refrigerator

Last Answer : Ans: a

Moisture in freon refrigeration system causes (a) ineffective refrigeration (b) high power consumption (c) freezing automatic regulating valve (d) corrosion of whole system

Description : Moisture in freon refrigeration system causes (a) ineffective refrigeration (b) high power consumption (c) freezing automatic regulating valve (d) corrosion of whole system

Last Answer : Ans: c

Choose the correct statement (a) A refrigerant should have low latent heat (b) If operating temperature of system is low, then refrigerant with low boiling point should be used (c) Pre-cooling and sub-cooling bf refrigerant are same (d) Superheat and sensible heat of a. refrigerant are same

Description : Choose the correct statement (a) A refrigerant should have low latent heat (b) If operating temperature of system is low, then refrigerant with low boiling point should be used (c) Pre-cooling and sub-cooling bf refrigerant are same (d) Superheat and sensible heat of a. refrigerant are same

Last Answer : Ans: b

The leaks in a refrigeration system using Freon are detected by (a) halide torch which on detection produces greenish flame lighting (b) sulphur sticks which on detection gives white smoke (c) using reagents (d) sensing reduction in pressure.

Description : The leaks in a refrigeration system using Freon are detected by (a) halide torch which on detection produces greenish flame lighting (b) sulphur sticks which on detection gives white smoke (c) using reagents (d) sensing reduction in pressure.

Last Answer : Ans: a

Aqua ammonia is used as refrigerant in the following type of refrigeration system (a) compression (b) direct (c) indirect (d) absorption

Description : Aqua ammonia is used as refrigerant in the following type of refrigeration system (a) compression (b) direct (c) indirect (d) absorption

Last Answer : Ans: d

A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure ofabout 67 kg/cm. The refrigerant used is (a) Ammonia (b) Carbon dioxide (c) Freon (d) Brine

Description : A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure ofabout 67 kg/cm. The refrigerant used is (a) Ammonia (b) Carbon dioxide (c) Freon (d) Brine

Last Answer : Ans: b