MODULE 1

Question 1

The primary purpose of a heat exchanger is to transfer energy from one fluid to another

Answer 1

a heat exchanger

Question 2

Heat exchangers
can be categorized according to the following:

Answer 2

Regenerators, Open-type exchangers, Close-type exchangers or recuperators

Question 3

These exchangers have hot and cold fluids flowing alternately through the same area with little to
no physical mixing between the two streams. The energy transfer is mainly dependent on the
properties of the fluid stream, and the geometry and thermal properties of the surface.

Answer 3

Regenerators

Question 4

____ are, as implied in their designation, devices wherein the physical
mixing of the two fluid streams occurs. Hot and cold fluids enter open-type heat exchangers and
leave as a single stream. The nature of the exit stream is predicted by continuity and the first law
of thermodynamics. No rate equations are necessary for the analysis of this type of exchanger.

Answer 4

Open-type heat exchangers

Question 5

are the most common and important type of heat exchanger. The hot and cold fluid
streams do not come into direct contact, and a tube wall or surface separates the two streams.
 Energy transfer is achieved through convection from one fluid to an intermediate surface, then by
conduction through the wall or plate, and finally by convection from the surface to the second
fluid.
 Recuperators are also categorized according to their configuration and the number of passes made
by each fluid stream as it flows inside the heat exchanger.

Answer 5

Recuperators

Question 6

TYPES OF HEAT EXCHANGERS

Answer 6

Double-pipe Heat Exchanger, Shell and tube Heat Exchanger, Compact Heat Exchanger, Printed circuit heat exchangers

Question 7

are one of the simplest types of heat exchangers which consist of
two concentric pipes of different diameters. In a double-pipe heat exchanger, one fluid flows
through the smaller pipe while the other fluid flows through the annular space between the two
pipes

Answer 7

Double-pipe Heat Exchanger

Question 8

Double-pipe heat exchangers have two types of flow arrangement:

Answer 8

parallel flow, counter flow

Question 8

both the hot and cold fluids enter the heat exchanger at the same end
and move in the same direction.

Answer 8

parallel flow

Question 9

___ heat exchangers have hot and cold fluids enter the heat
exchanger at the opposite ends and flow in opposite directions.

Answer 9

counter flow

Question 10

-are the most common type of heat exchanger in industrial
applications

-These heat exchangers contain large number of tubes (sometimes several hundred) packed in a
shell with their axes parallel to that of the shell. Heat transfer takes place as one fluid flows inside
the tubes while the other fluid flows outside the tubes through the shell.

-are not suitable for use in automotive and aircraft applications
because of their relatively large size and weight.

-are further classified according to the number of shell and tube
passes involved.

Answer 10

Shell and tube Heat Exchanger

Question 11

are designed to realize a large heat transfer surface area per unit
volume. This type allows high heat transfer rates between two fluids to be achieved in a small
volume. Compact heat exchangers usually have small flow passages, and the flow is considered
to be laminar.

are also used in gas-to-gas and gas-to-liquid (or liquid-to-gas) heat
exchangers to counteract the low heat transfer coefficient associated with gas flow with increased
surface area. The two fluids usually move perpendicular to each other, and such flow configuration
is called cross-flow. The cross-flow is further classified as unmixed and mixed flow, depending on
the flow configuration,

Answer 11

Compact Heat Exchanger

Question 12

(PCHE) are compact heat exchangers widely used today in
industrial applications such as chemical processing, fuel processing, waste heat recovery, and
refrigeration. The PCHEs are usually made from stainless steel, titanium, copper, nickel, and nickel
alloys to withstand operating pressures up to 500 bar.

Answer 12

Printed circuit heat exchangers

Question 13

PCHE means

Answer 13

Printed circuit heat exchangers

Question 13

Other Types of Heat Exchangers

Answer 13

Plate and frame heat exchangers, Regenerative heat exchangers

Question 13

consist of a series of plates with corrugated flat flow passages
(Figure 5). The hot and cold fluids flow in alternate passages, and thus each cold fluid stream is
surrounded by two hot fluid streams, resulting in very effective heat transfer.

can grow with increasing demand for heat transfer by simply mounting more
plates. They are well ideal for liquid-to-liquid heat exchange applications, provided that the hot
and cold fluid streams are at about the same pressure.

Answer 13

Plate and frame heat exchangers

Question 14

can be a static-type or dynamic-type.

Answer 14

Regenerative heat exchangers

Question 15

___ regenerative heat exchanger is porous that has a large heat storage capacity, like a
ceramic wire mesh. Heat is transferred from the hot fluid to the matrix of the regenerator during
the flow of the hot fluid, and from the matrix to the cold fluid during the flow of the cold fluid.

Answer 15

Static-type

Question 15

LMTD means

Answer 15

log mean temperature difference

Question 15

___ regenerator involves a rotating drum and continuous flow of the hot and cold fluid
through different portions of the drum so that any portion of the drum passes periodically through
the hot stream, storing heat, and then through the cold stream, rejecting this stored heat.

Answer 15

Dynamic-type