Heat transfer - Food Engineering - Life Sciences Previous Year Questions

1

2013 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2013

A cold storage plant is used for storing 50 tonnes of apples in perforated plastic crates. During the storage, apples are cooled down from 28°C to storage temperature of 2°C. (Specific heat of the apple = 0.874 kcal kg⁻¹ °C⁻¹). If the required cooling is attained in 16 hours, the refrigeration plant capacity (in Tons) is

A

19

B

24

C

29

D

32

Check answer

Open complete paper

2

2014 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2014

In a counter-current double pipe heat-exchanger, milk is cooled from 110 to 40°C using chilled water as coolant. Water enters at 5°C and leaves at 60°C. Heat flux for the system with overall heat transfer coefficient of 950 W m⁻² K⁻¹ will be ______ W m⁻².

Check answer

Open complete paper

3

2016 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2016

Condensing steam is used to heat vegetable oil in a double pipe co-current heat exchanger. If the inlet and outlet temperature of steam are T_hi and T_ho, and for vegetable oil T_ci and T_co respectively, the log mean temperature difference (ΔT_LM) will be ________ .

A

\(\frac{T_{hi} - T_{co}}{\ln \frac{T_{hi} - T_{co}}{T_{ho} - T_{ci}}}\)

B

\(\frac{(T_{ho} - T_{ci}) - (T_{hi} - T_{co})}{\ln \frac{T_{ho} - T_{ci}}{T_{hi} - T_{co}}}\)

C

\(\frac{(T_{hi} - T_{co}) - (T_{ho} - T_{ci})}{\ln \frac{T_{hi} - T_{co}}{T_{ho} - T_{ci}}}\)

D

\(\frac{T_{ho} - T_{ci}}{\ln \frac{T_{hi} - T_{co}}{T_{ho} - T_{ci}}}\)

Open complete paper

4

2017 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2017

Water flowing at a rate of 1 kg/min is heated from 12 to 80 °C with flue gas supplied at a rate of 3 kg/min. The temperature and specific heat of the flue gas are 180 °C and 1.05 kJ/kg.K, respectively. If specific heat of water is 4.2 kJ/kg.K and the flow is parallel, then the logarithmic mean temperature difference will be ______°C.

Check answer

Open complete paper

5

2018 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2018

Ambient air at 30°C dry bulb temperature and 80% relative humidity was heated to a dry bulb temperature of 80°C in a heat exchanger by indirect heating. The amount of moisture gain (g kg^-1 dry air) during the process would be ______.

Check answer

Open complete paper

6

2018 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2018

The rate of heat transfer per unit area from a metal plate is 1000 W m⁻². The surface temperature of the plate is 120°C and ambient temperature is 20°C. The convective heat transfer coefficient (W m⁻² °C⁻¹) using the Newton’s law of cooling will be ______.

Check answer

Open complete paper

7

2019 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2019

A mixed fruit beverage with 12 °Brix having specific heat of 4298 J kg⁻¹ K⁻¹ is being heated from 30 °C to 95 °C for pasteurization at a flow rate of 1000 L h⁻¹ in a tubular heat exchanger. Steam at 100 °C is used as heating medium which is converted into condensate at 100 °C. If the density of beverage is 1075 kg m⁻³ and the latent heat of steam at the given temperature is 2257 kJ kg⁻¹, the mass flow rate of steam (kg min⁻¹) is ______ (round off to 2 decimal places).

Check answer

Open complete paper

8

2019 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2019

Freezing of 100 mm spherical meat ball with 60% moisture at 35 °C is being done in an air blast freezer maintained at -45 °C. Given, latent heat of fusion for water is 333.2 kJ kg⁻¹, thermal conductivity of meat is 1.5 W m⁻¹ °C⁻¹, convective heat transfer coefficient is 40 W m⁻² °C⁻¹, density of frozen meat is 980 kg m⁻³ and initial freezing temperature of meat ball is -10 °C. Using Plank’s equation, freezing time (h) is ______ (round off to 2 decimal places).

Check answer

Open complete paper

9

2022 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2022

In a dairy plant, spray drying technology is used to produce whey powder. The rate of spray drying depends on

A

Temperature of the incoming air

B

Shape of the cyclone separator

C

Diameter of the whey droplet

D

Heat transfer coefficient of hot air

Check answer

Open complete paper

10

2022 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2022

Which among the following expression(s) is/are correct?

A

Reynolds number = \frac{Density \times Velocity \times Characteristic\ dimension}{Viscosity}

B

Nusselt number = \frac{Convective\ heat\ transfer\ coefficient \times Characteristic\ dimension}{Thermal\ conductivity\ of\ solid}

C

Schmidt number = \frac{Kinematic\ viscosity\ of\ fluid}{Diffusivity}

D

Biot number = \frac{Convective\ heat\ transfer\ coefficient \times Characteristic\ dimension}{Thermal\ conductivity\ of\ fluid}

Check answer

Open complete paper

11

2022 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2022

In a dairy processing plant, milk enters a 30 m long and 2 cm diameter tube at 60 °C and leaves at 57 °C. The total heat loss over the tube length is 381.15 W. The specific heat capacity, density, and viscosity of milk are 3.85 kJ kg⁻¹ K⁻¹, 1020 kg m⁻³, and 1.20 cP, respectively. The Reynolds number for the flow is ______ (round off to the nearest integer).
Given: π = 3.14

Check answer

Open complete paper

12

2026 · Life Sciences · Food Engineering · Heat transfer

Life Sciences (XL) 2026

Hot oil is being cooled in a countercurrent, double-pipe heat exchanger from 410 K to 340 K by chilled water entering at 290 K and exiting the exchanger at 330 K. The Log Mean Temperature Difference (LMTD) for this heat transfer is ______K. (Round off to one decimal place)

Check answer

Open complete paper