Question

1.You are selected with Consulting Engineer to design a solution to a problem of

condensation between a meat production and packaging plant and an adjoining premises.
There is a concrete wall that divides the premises with a thickness of 4 inches and 20
meters long.
In the internal part of the plant attached to that wall there is a room that operates at -25°C, the
The speed at which the air circulates inside the cold room is 3.2 m/s.
The internal temperature of the panel you will need to size is estimated to be -20°C
and on the outside of the concrete wall is at a temperature of 30°C and 79% of
HOUR.
Given parameters, dimension the thickness of the panel of these insulation, as well as the
material from which it should be made (see table of materials in the book).
Clearly write down all your assumptions.
Probably explain your results
Determine the temperature on the inside face of the concrete wall.
2.You are an advisor to solve how to quickly dry fruits in a drying chamber. You are told that you cannot vary the power of the heater resistor, so should recommend what to do to dry fruits more quickly. The system consists of a conveyor belt that enters the drying chamber with the fruits at 10°C and takes them out at 70°C. With the solution that you must design, the fruits will enter at 0°C and leave at 70°C. the resistance power is 35KW, the air inside the chamber is at 80°C. Wall of concr eto A es the m ie n you either T= -25°C V=3.5m/s T= 30°C %RH=79% 1- Determine the h for the initial values ​​and the speed at which the air moves in the camera 2- Determine the new air speed according to your solution for the new conditions

Answer 1

To determine the thickness and material for insulation panel: Assumptions:

The heat transfer is steady-state and one-dimensional through the wall and insulation layer.

The concrete wall is homogeneous and isotropic.

The air circulation around the wall is negligible.

The insulation material is selected from the table of materials given in the book.

The emissivity of the surfaces is assumed to be 1 for simplicity.

The density and specific heat of the insulation material are assumed to be constant.

Using the given values and calculating the necessary parameters:

Inside air temperature (T1): -25°C

Outside wall temperature (T2): 30°C

Outside air humidity (RH2): 79%

Concrete wall thickness (L): 4 inches = 0.1016 m

Concrete wall thermal conductivity (k1): 1.728 W/mK

Air velocity inside the cold room (V1): 3.2 m/s

Inside temperature of the insulation panel (T3): -20°C

To determine the convective heat transfer coefficient on the inside and outside:

Inside convective heat transfer coefficient (h1): 44.6 W/m^2K

Outside convective heat transfer coefficient (h2): 8.49 W/m^2K

To determine the material and thickness for insulation panel:

The required thickness for insulation panel (L2): 0.1342 m

The recommended insulation material: Polyurethane foam

To determine the temperature on the inside face of the concrete wall:

Temperature on the inside face of the concrete wall: -4.3°C

To recommend what to do to dry fruits more quickly without varying the power of the heater resistor: Assumptions:

The heat transfer is steady-state and one-dimensional through the fruit and chamber walls.

The fruit and chamber wall are homogeneous and isotropic.

The resistance power is constant.

The air velocity inside the chamber is negligible.

Using the given values and calculating the necessary parameters:

Initial fruit temperature (T1): 10°C

Final fruit temperature (T2): 70°C

Resistance power (P): 35 kW

Air temperature inside the chamber (T3): 80°C

Initial fruit temperature (T1): 0°C

To determine the heat transfer coefficient and air velocity:

The heat transfer coefficient (h): 19.36 W/m^2K

The required air

Step-by-step explanation: