Hot questions in Heat Transfer / GO Mechanical

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GATE ME 2013 | Question: 50
Water (specific heat, $c_p$ = $4.18$ $kJ$/$kgK$) enters a pipe at a rate of $0.01 kg/s$ and a temperature of $20^ \circ C$.The pipe, of diameter $50$ $mm$ and length $3$ $m$, is subjected to a wall heat flux ${q_{w}}''$ in $W$ ... ($x = 0$ at the inlet), the bulk mean temperature of the water leaving the pipe in $^\circ \textrm{C}$ is $42$ $62$ $74$ $104$

Water (specific heat, $c_p$ = $4.18$ $kJ$/$kgK$) enters a pipe at a rate of $0.01 kg/s$ and a temperature of $20^ \circ C$.The pipe, of diameter $50$ $mm$ and length $3$ ...

piyag476

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piyag476 asked Feb 19, 2017

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GATE Mechanical 2014 Set 2 | Question: 16
In a heat exchanger, it is observed that $ΔT_1$ = $ΔT_2$, where $ΔT_1$ is the temperature difference between the two single phase fluid streams at one end and $ΔT_2$ is the temperature difference at the other end. This heat exchanger is a condenser an evaporator a counter flow heat exchanger a parallel flow heat exchanger

In a heat exchanger, it is observed that $ΔT_1$ = $ΔT_2$, where $ΔT_1$ is the temperature difference between the two single phase fluid streams at one end and $ΔT_2$ ...

Arjun

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Arjun asked Feb 19, 2017

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GATE ME 2013 | Question: 30
A steel ball of diameter $60$ $mm$ is initially in thermal equilibrium at $1030^0C$ in a furnace. It is suddenly removed from the furnace and cooled in ambient air at $30^0C$, with convective heat transfer coefficient $h = 20 W/m^2K$. The thermo-physical ... required in seconds to cool the steel ball in air from $1030^0C$ to $430^0C$ is $519$ $931$ $1195$ $2144$

A steel ball of diameter $60$ $mm$ is initially in thermal equilibrium at $1030^0C$ in a furnace. It is suddenly removed from the furnace and cooled in ambient air at $30...

piyag476

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piyag476 asked Feb 19, 2017

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GATE ME 2013 | Question: 8
The pressure, dry bulb temperature and relative humidity of air in a room are $1$ bar, $30^{\circ} C$ and $70\%$, respectively. If the saturated steam pressure at $30^{\circ} C$ is $4.25$ $kPa$, the specific humidity of the room air in $kg$ water $\text{vapour/kg}$ dry air is $0.0083$ $0.0101$ $0.0191$ $0.0232$

The pressure, dry bulb temperature and relative humidity of air in a room are $1$ bar, $30^{\circ} C$ and $70\%$, respectively. If the saturated steam pressure at $30^{\c...

piyag476

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piyag476 asked Feb 19, 2017

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GATE Mechanical 2014 Set 4 | Question: 24
Match the heat treatment processes (Group A) and their associated effects on properties (Group B) of medium carbon steel ... $P-III, Q-II, R-IV, S-I$ $P-II, Q-III, R-I, S-IV$

Match the heat treatment processes (Group A) and their associated effects on properties (Group B) of medium carbon steel$\begin{array}{|l|l|} \hline \textbf{Group A} & \t...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 3 | Question: 17
A sample of moist air at a total pressure of $85$ $kPa$ has a dry bulb temperature of $30^oC$ (saturation vapour pressure of water = $4.24$ $kPa$). If the air sample has a relative humidity of $65$%, the absolute humidity (in gram) of water vapour per $kg$ of dry air is _______

A sample of moist air at a total pressure of $85$ $kPa$ has a dry bulb temperature of $30^oC$ (saturation vapour pressure of water = $4.24$ $kPa$). If the air sample has ...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 4 | Question: 15
Match Group A with Group B: ... $P-4, Q-3, R-1, S-2$ $P-3, Q-2, R-1, S-4$ $P-2, Q-1, R-3, S-4$

Match Group A with Group B:$\begin{array}{|l|l|} \hline \textbf{Group A} & \textbf{Group B} \\ \hline \text{P: Biot number} & \text{1: Ratio of buoyancy to viscous force}...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 3 | Question: 47
A solid sphere of radius $r_1 = 20$ $mm$ is placed concentrically inside a hollow sphere of radius $r_2 = 30$ $mm$ as shown in the figure. The view factor $F_{21}$ for radiation heat transfer is $\dfrac{2}{3} \\$ $\dfrac{4}{9} \\$ $\dfrac{8}{27} \\$ $\dfrac{9}{4}$

A solid sphere of radius $r_1 = 20$ $mm$ is placed concentrically inside a hollow sphere of radius $r_2 = 30$ $mm$ as shown in the figure.The view factor $F_{21}$ for ra...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 3 | Question: 16
A source at a temperature of $500$ $K$ provides $1000$ $kJ$ of heat. The temperature of environment is $27^oC$. The maximum useful work (in $kJ$) that can be obtained from the heat source is _______

A source at a temperature of $500$ $K$ provides $1000$ $kJ$ of heat. The temperature of environment is $27^oC$. The maximum useful work (in $kJ$) that can be obtained fro...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 2 | Question: 12
For laminar forced convection over a flat plate, if the free stream velocity increases by a factor of $2$, the average heat transfer coefficient remains same decreases by a factor of $\sqrt{2}$ rises by a factor of $\sqrt{2}$ rises by a factor of $\sqrt{4}$

For laminar forced convection over a flat plate, if the free stream velocity increases by a factor of $2$, the average heat transfer coefficientremains samedecreases by a...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 2 | Question: 44
A material P of thickness $1$ $mm$ is sandwiched between two steel slabs, as shown in the figure below. A heat flux $10$ $kW/m^2$ is supplied to one of the steel slabs as shown. The boundary temperatures of the slabs are indicated ... steady state heat conduction for the configuration, the thermal conductivity ($k$, in $W/m.K$) of material $P$ is _______

A material P of thickness $1$ $mm$ is sandwiched between two steel slabs, as shown in the figure below. A heat flux $10$ $kW/m^2$ is supplied to one of the steel slabs as...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 1 | Question: 48
A reversible heat engine receives $2$ $kJ$ of heat from a reservoir at $1000$ $K$ and a certain amount of heat from a reservoir at $800$ $K$. It rejects $1$ $kJ$ of heat to a reservoir at $400$ $K$. The net work output (in $kJ$) of the cycle is $0.8$ $1.0$ $1.4$ $2.0$

A reversible heat engine receives $2$ $kJ$ of heat from a reservoir at $1000$ $K$ and a certain amount of heat from a reservoir at $800$ $K$. It rejects $1$ $kJ$ of heat ...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 2 | Question: 13
The thermal efficiency of an air-standard Brayton cycle in terms of pressure ratio $r_p$ and $\gamma (= c_p /c_v)$ is given by $1-\dfrac{1}{{r_p}^{\gamma -1}} \\$ $1-\dfrac{1}{{r_p}^{\gamma }} \\$ $1-\dfrac{1}{{r_p}^{1/\gamma }} \\$ $1-\dfrac{1}{{r_p}^{(\gamma -1)/\gamma }}$

The thermal efficiency of an air-standard Brayton cycle in terms of pressure ratio $r_p$ and $\gamma (= c_p /c_v)$ is given by$1-\dfrac{1}{{r_p}^{\gamma -1}} \\$$1-\dfrac...

Arjun

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Arjun asked Feb 19, 2017