MCQ
1. Thermal conductivity of air with rise in temperature-
Thermal conductivity of any material is dependent on two things:
i)The motion of free electrons
ii) Lattice vibrations
Thermal conductivity of liquids decreases with increasing temperature as the liquid expands and the molecular move apart.
In the case of solids because of lattice distortings higher temperatures make it difficult for electrons to flow, hence the thermal conductivity of metals decreases at non-metals, electronic conductivity is practically non-existent and due to an increase in phonon conduction, the thermal conductivity increases.
increases
decreases
remains constant
both increases and decreases
2. In vapour compression cycle using NH, as refrigerant, initial charge is filled at-.
suction of compressor
delivery of compressor
high pressure side close to receiver
low pressure side near receiver
3. মধ্যবর্তী মাধ্যমের বিচ্যুতি গরম বস্তু হতে ঠান্ডা বস্তুতে সরল রেখার হিট ট্রান্সফার প্রক্রিয়াকে কী বলে?
কনডাকশন
রেডিয়েশন
কনভেকশন
একটিও না
4. In vapor compression cycle the condition off refrigerant is dry saturated vapour—
after passing through the condenser
before entering the compressor
after passing through the expansion or throttle valve
before passing through the condenser
5. In vapour compression cycle, the condition of refrigerant is high pressure saturated liquid-.
after passing through the condenser
before passing through the condenser
after passing through the expansion or throttle valve
before entering the expansion valve
6. The evolution of heat of solution takes place in ammonia absorption plant when--
ammonia vapour goes into solution
ammonia vapour is driven out of solution
lithium bromide mixes with ammonia
weak solution mixes with strong solution
7. The moisture in None of these refrigerant is removed by-
evaporator
denumidifier
driers
safety relief valve
8. In vapour compression cycle, the condition of refrigerant is superheated vapour-.
after passing through the condenser
before passing through the condenser
after passing through the expansion or throttle valve
before entering the expansion valve
9. তরল ও বায়বীয় পদার্থের ক্ষেত্রে হিট ট্রান্সফার সংঘটিত হয় যে উপায়ে, তাকে কী বলে?
কনডাকশন
কনভেকশন
রেডিয়েশন
কোনোটিই নয়
10. The COP of a vapor compression plant in comparison to vapor absorption plant is-
more
same
less
unpredictable
11. The wet bulb temperature at 100% relative humidity is-- dew point temperature.
Same as
Higher than
Lower than
none
12. Clapeyron equation is a relation between-
temperature, pressure specific volur and enthalpy
temperature, pressure and enthalpy
specific volume and enthalpy
temperature and enthalpy
13. In vapour compression cycle, the condition of refrigerant is saturated liquid-
after passing through the condenser
after passing through the condenser
after passing through the expansion throttle valve
before entering the expansion valve
14. Mass flow ratio of NH3 in comparison to Freon-12 for same refrigeration load and same temperature limits is of the order of-
1:1
9:1
1:9
1:3
15. Ammonia is-.
non-toxic
non-inflammable
toxic and non-inflammable
highly toxic and inflammable
16. An important characteristic of absorption system of refrigeration is--.
noisy operation
quiet operation
cooling below 0°C
very little power consumption
17. In vapour compression cycle, the condition of refrigerant is very wet vapour-.
after passing through the condenser
betore passing through the condenser
after passing through the expansion or throttle valve
before entering the compressor
18. Freon group of refrigerants are-.
inflammable
toxic
non-inflammable and toxic
non-toxic and non-inflammable
19. The vapour compression refrigeratór employs the following cycle-.
Rankine
Carnot
Reversed Carnot
Reversed Rankine
20. The COP of a domestic refrigerator in comparison to domestic air conditioner will be --
same
less
more
unpredictable