MCQ
2161.
A diathermic wall is one which-
Prevents thermal interaction
Permits thermal interaction
Encourages thermal interaction
Discourages thermal interaction
2162.
An ideal gas obeys the law-
PT = nR ̅V
PV=n/R ̅T
PV= nR ̅T
PV= nR ̅/T
2163.
In vapour compresion refrigeration system, refrigerant occurs as liquid between-.
condeuser and expäision valve
compressor and evaporator
expansion valve and evaporator
compressor and condenser
2164.
Bull bearing is usually made from-
low carbon steel
high carbon steel
chrome steel
medium carbon steel
2165.
A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67kg/cm The refrigerant used is--
Ammonia
Carbon dioxide
Freon
Brine
2166.
A path 1-2-3 is given. A system absorbs 100 kj as heat and does 60kj of work while along the path 1-4-3, it does 20kj of work. The heat absorbed during the cycle 1-4-3 is-
-140kj
-80kj
-40kj
+60kj
Himalay Sen Sir
মেকানিক্যাল ইঞ্জিনিয়ারিং MCQ
থার্মোডায়নামিক্স mcq
mechanical mcq
মেকানিক্যাল বিগত সালের প্রশ্ন সমাধান
ব্যাখ্যা: For 1-2-3 cycle.
𝘘1-2-3 = 100 kj
W1-2-3 = 60 kj
We know,
Heat = Internal energy + Work
𝘘1-2-3 = 𝘘1-2-3 + W1-2-3
𝘘1-2-3 = 𝘘1-2-3 - W1-2-3
𝘘1-2-3 = (100-60) kj = 40 kj
Again, For 1-4-3 cycle,
W1-4-3 = 20kj
𝘘1-2-3 = 𝘘1-4-3 =40kj
Again, we know,
𝘘1-4-3 = 𝘘1-4-3 + W1-4-3
= 40 kj+20 kj = 60 kj
For 1-2-3 cycle.
𝘘1-2-3 = 100 kj
W1-2-3 = 60 kj
We know,
Heat = Internal energy + Work
𝘘1-2-3 = 𝘘1-2-3 + W1-2-3
𝘘1-2-3 = 𝘘1-2-3 - W1-2-3
𝘘1-2-3 = (100-60) kj = 40 kj
Again, For 1-4-3 cycle,
W1-4-3 = 20kj
𝘘1-2-3 = 𝘘1-4-3 =40kj
Again, we know,
𝘘1-4-3 = 𝘘1-4-3 + W1-4-3
= 40 kj+20 kj = 60 kj
2167.
Aqua ammonia is used as refrigerant in the following type of refrigeration system--
compression
indirect
absorption
direct
2168.
In a throttling process-
In a throttling process-
Temperature remains constant
Enthalpy remains constant
Volume remains constant
2169.
Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system-
strong solution is weak solution
weak solution to strong solution
atozng solution to ammonia vapour
ammonia vapour to weak solution
2170.
In a refrigeration cycle, the flow of refrigerant is controlled by –
compressor
evaporator
expansion valve
condenser
2171.
The human body feels comfortable who the heat stored in the body is.
positive
zero
negative
none
2172.
Efficiency of a Carnot engine is given as 80%. If the cycle direction he reversed, what will be the value of COP of reversed Carnut cycle?
125
0.5
0.25
0.8
2173.
An adiabatic wall is one which-
Prevents thermal interaction
Permits thermal interaction
Encourages thermal interaction
Discourages thermal interaction
2174.
Where does the lowest temperature occur in a vapour compression cycle?
condenser
compressor
evaporator
expansion valve
2175.
At lower temperatures and pressures, the latent heat of vapourisation of a refrigerant-
decreases
increases
remains same
depends on other factors
2176.
Accumulators should have adequate volume to store refrigerant charge at least-
10%
50%
25%
75%
2177.
In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to--
collect liquid refrigerant and prevent it from going to compressor
detect liquid in vapour
superheat the vapour
collect vapours
2178.
An evaporator is also known as—
cooling coil
freezing coil
chilling cod
all of these
2179.
Change in entropy in a irreversible process-
Ds>d𝘘
ds< d𝘘/T
Ds= d𝘘/T
De ɑ d𝘘 /T
2180.
Calorie is a measure of-
Specific heat
Quantity of heat
Thermal capacity
Entropy