The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same. (A) Kinematic viscosity (B) Work (C) Temperature (D) None of these

The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same. (A) Kinematic viscosity
(B) Work
(C) Temperature
(D) None of these
by

1 Answer

Answer :

(D) None of these
by

Related questions

Co-efficient of Performance (COP) of a refrigerator is the ratio of the (A) Work required to refrigeration obtained (B) Refrigeration obtained to the work required (C) Lower to higher temperature (D) Higher to lower temperature

Description : Co-efficient of Performance (COP) of a refrigerator is the ratio of the (A) Work required to refrigeration obtained (B) Refrigeration obtained to the work required (C) Lower to higher temperature (D) Higher to lower temperature

Last Answer : (B) Refrigeration obtained to the work required

Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)? (A) Air cycle (B) Carnot cycle (C) Ordinary vapour compression cycle (D) Vapour compression with a reversible expansion engine

Description : Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)? (A) Air cycle (B) Carnot cycle (C) Ordinary vapour compression cycle (D) Vapour compression with a reversible expansion engine

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Diffusion co-efficient generally depends upon the temperature, pressure & the nature of the components of the system. Its dimension is not the same as that of the (A) Mass transfer co-efficient (B) Thermal diffusivity (C) Kinematic viscosity (D) Volumetric diffusivity

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Which of the following is not dimension-less? (A) Froude number (B) Kinematic viscosity (C) Pressure co-efficient (D) None of these

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The drag co-efficient for a bacterium moving in water at 1 mm/s, will be of the following order of magnitude (assume size of the bacterium to be 1 micron and kinematic viscosity of water to be 10 -6m2 /s). (A) 24000 (B) 24 (C) 0.24(D) 0.44

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Which of the following is not a dimension-less parameter? (A) Pressure-co-efficient (B) Froude number (C) Kinematic viscosity (D) Weber number

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The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are (A) (COP)R = (COP)HP = 0.6 (B) (COP)R = 2.5; (COP)HP = 1.5 (C) (COP)R = 1.5; (COP)HP = 2.5 (D) (COP)R = (COP)HP = 2.5

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The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is (A) Less (B) More (C) Same (D) Dependent on climatic conditions

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Last Answer : (A) Less

The ratio of absolute viscosity to mass density is known as (A) Specific viscosity (B) Viscosity index (C) Kinematic viscosity (D) Coefficient of viscosity

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The kinematic viscosity (in stoke) and the absolute/dynamic viscosity (in poise) are the same for __________ at room temperature. (A) Air (B) Water (C) Mercury (D) Alcohol

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Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in (A) Increased COP (B) Same COP (C) Decreased COP (D) Increased or decreased COP; depending upon the type of refrigerant

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Last Answer : (A) Increased COP

The ratio of kinematic viscosity to thermal diffusivity is called the __________ number. (A) Peclet (B) Prandtl (C) Stanton (D) Nusselt

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The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is (A) Less pronounced (B) More pronounced (C) Equal (D) Data insufficient, can't be predicted

Description : The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is (A) Less pronounced (B) More pronounced (C) Equal (D) Data insufficient, can't be predicted

Last Answer : (B) More pronounced

In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respectively, the Carnot COP will be (A) 5.2 (B) 6.2 (C) 0.168 (D) Data insufficient, can't be found out

Description : In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respectively, the Carnot COP will be (A) 5.2 (B) 6.2 (C) 0.168 (D) Data insufficient, can't be found out

Last Answer : A) 5.2

Double pipe heat exchangers are preferably useful, when (A) High viscosity liquid is to be cooled (B) Requirement of heat transfer area is low (C) Overall heat transfer co-efficient is very high (D) A corrosive liquid is to be heated

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Last Answer : (B) Requirement of heat transfer area is low

. Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water. (A) Boiling point (B) Dynamic viscosity (C) Kinematic viscosity (D) Density

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The unit of kinematic viscosity in S. I. units is (A) N-m/s (B) N-s/m2 (C) m 2 /s (D) N-m

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The units of kinematic viscosity are (A) Metres² per sec (B) kg sec/metre (C) Newton-sec per metre (D) Newton-sec per metre

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Stoke is the unit of (A) Kinematic viscosity in C. G. S. units (B) Kinematic viscosity in M. K. S. units (C) Dynamic viscosity in M. K. S. units (D) Dynamic viscosity in S. I. units

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What is the value of maximum COP in case of absorption refrigeration, if refrigeration provided is at temperature, TR (where, T1 and T2 are source & surrounding temperatures respectively.)? (A) TR/(T2 - TR) × (T1 - T2 )/T1 (B) TR/(T2 - TR) × T1 /(T1 - T2 ) (C) TR/(T1 - TR) × (T1 - T2 )/T1 (D) None of these

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A refrigerator is working on reversed carnot cycle between temperature of 30°C to –10°C with capacity of 10 tonnes. Calculate. (i) The COP (ii) Define ton of refrigeration (iii) Give the industrial application of refrigeration

Description : A refrigerator is working on reversed carnot cycle between temperature of 30°C to –10°C with capacity of 10 tonnes. Calculate. (i) The COP (ii) Define ton of refrigeration (iii) Give the industrial application of refrigeration

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The kinematic viscosity is the (A) Ratio of absolute viscosity to the density of the liquid (B) Ratio of density of the liquid to the absolute viscosity (C) Product of absolute viscosity and density of the liquid (D) Product of absolute viscosity and mass of the liquid

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COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about (A) 0.5 (B) 3.5 (C) 4.5 (D) 8.5

Description : COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about (A) 0.5 (B) 3.5 (C) 4.5 (D) 8.5

Last Answer : (B) 3.5

Which of the following has the minimum value of COP for a given refrigeration effect? (A) Reverse Carnot cycle (B) Ordinary vapour-compression cycle (C) Vapour-compression process with a reversible expansion engine (D) Air refrigeration cycle

Description : Which of the following has the minimum value of COP for a given refrigeration effect? (A) Reverse Carnot cycle (B) Ordinary vapour-compression cycle (C) Vapour-compression process with a reversible expansion engine (D) Air refrigeration cycle

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Out of the following refrigeration cycles, which one has maximum COP? (A) Air cycle (B) Carnot cycle (C) Ordinary vapor compression cycle (D) Vapor compression with a reversible expansion engin

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The dimension of diffusivity is same as that of the (A) Density (B) Molal concentration (C) Kinematic viscosity (D) Velocity head

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Which of the following has the same dimension as mass diffusivity? (A) Momentum flux (B) Kinematic viscosity (C) Thermal diffusivity (D) Both (B) and (C)

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Dimension of mass diffusivity is the same as that of (A) Kinematic viscosity (B) Dynamic viscosity (C) Surface tension (D) Pressure

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Newton's law of viscosity, which states that the shear stress is proportional to the __________ Co-efficient of viscosity is called dynamic or absolute viscosity(where, V = velocity, Vg = velocity gradient). (A) V2 (B) 1/V2 (C) 1/Vg (D) Vg

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The film co-efficient between condensing vapour and metal wall increases with (A) Increasing temperature of the vapour (B) Decreasing temperature of the vapour (C) Increasing viscosity of the film of condensate (D) Increasing temperature drop

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The coefficient of performance (COP) is the ratio between the:  A. Power consumption in watts and heat absorbed per hour  B. Heat absorbed per hour and the power consumption in watts  C. Work required and the absorbed heat  D. Absorbed heat and work required

Description : The coefficient of performance (COP) is the ratio between the:  A. Power consumption in watts and heat absorbed per hour  B. Heat absorbed per hour and the power consumption in watts  C. Work required and the absorbed heat  D. Absorbed heat and work required

Last Answer : Absorbed heat and work required

Kinematic index of the straw Walker is as ratio (a) Angular velocity of straw Walker to angular velocity of threshing drum (b) Angular velocity of straw Walker to angular velocity of threshing drum (c) Angular velocity of straw Walker to linear velocity of combine (d) All of the above

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The ratio of reel peripheral speed to forward speed of combine is called (a)velocity index (b)angular velocity index (c)reel speed index (d) kinematic index

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The ratio of real peripheral speed to forward speed of combine is called :- a) Velocity index b) Angular velocity index C) Reel speed index d) kinematic index

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Under-cooling in a refrigeration cycle (a) increases COP (b) decreases COF (c) COP remains unaltered (d) other factors decide COP

Description : Under-cooling in a refrigeration cycle (a) increases COP (b) decreases COF (c) COP remains unaltered (d) other factors decide COP

Last Answer : Ans: a

Superheating in a refrigeration cycle (a) increases COP (b) decreases COP (c) COP remains unaltered (d) other factors decide COP

Description : Superheating in a refrigeration cycle (a) increases COP (b) decreases COP (c) COP remains unaltered (d) other factors decide COP

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What is the use of flash chamber in a vapour compression refrigeration cycle to improve the COP of refrigeration cycle ?

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. One stoke (unit of kinematic viscosity) is equivalent to (A) 1 cm2 /second (B) 1 m2 /second (C) 1 gm/cm. second (D) 1 kg. m/second

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Which of the following is a dimensionless parameter? (A) Angular velocity (B) Specific weight (C) Kinematic viscosity (D) None of these

Description : Which of the following is a dimensionless parameter? (A) Angular velocity (B) Specific weight (C) Kinematic viscosity (D) None of these

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N. second/m2 is (A) The S.I. unit of dynamic viscosity (B) The S.I. unit of kinematic viscosity (C) Equivalent to one poise (D) Equivalent to one stoke

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The dimension of kinematic viscosity is(A) ML -2T -1 (B) L 2T -1 (C) ML -2T -2 (D) None of these

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Pick out the wrong statement: (A) Greater is the kinematic viscosity of the liquid, greater is the thickness of the boundary layer (B) Blowers develop a maximum pressure of 2 atmospheres (C) Friction losses in pipe fittings are generally expressed in terms of velocity heads (D) Fanning friction factor in case of turbulent flow of liquids in pipe depends upon relative roughness & Reynolds number

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Joule-Thomson co-efficient which is defined as, η = (∂T/∂P)H = 1/Cp (∂H/∂T)P, changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is (A) 0 (B) ∞ (C) +ve (D) -ve

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Last Answer : (A) 0

Which one is the correct relation between energy efficiency ratio (EER) and coefficient of performance (COP)?  A. EER = 2.34 COP  B. EER = 3.24 COP  C. EER = 3.42 COP  D. EER = 4.23 COP

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Last Answer : EER = 3.42 COP

Heat transfer by natural convection is enhanced in system with (A) High viscosity (B) High co-efficient of thermal expansio

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The ratio of settlement at any time 't' to the final settlement, is known as (A) Co-efficient of consolidation (B) Degree of consolidation (C) Consolidation index (D) Consolidation of undisturbed soil

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Which of the following is an undesirable property of a manometricliquid? (A) Non-sticky & non-corrosive nature (B) High vapour pressure (C) Low viscosity & surface tension (D) Low co-efficient of thermal expansion

Description : Which of the following is an undesirable property of a manometricliquid? (A) Non-sticky & non-corrosive nature (B) High vapour pressure (C) Low viscosity & surface tension (D) Low co-efficient of thermal expansion

Last Answer : (B) High vapour pressure

12. Kinematic viscosity is the product of dynamic viscosity and the density of the liquid. A) Yes B) No

Description : 12. Kinematic viscosity is the product of dynamic viscosity and the density of the liquid. A) Yes B) No

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Kinematic viscosity is dependent upon (A) Pressure (B) Distance (C) Density (D) Flow

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Which of the following is the unit of kinematic viscosity? (A) Pascal (B) Poise (C) Stoke (D) Faraday

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