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An ideal Rankine cycle operates with turbine inlet steam at 90 bar and 500°C, and a condenser at 40 °C. Calculate the efficiency

lilavasa [31]

Answer:

40.8%

Explanation:

A rankine cycle is a generation cycle using water as a working fluid, when heat enters the boiler the water undergoes a series of changes in state and energy until generating power through the turbine.

This cycle is composed of four main components, the boiler, the pump, the turbine and the condenser as shown in the attached image

To solve any problem regarding the rankine cycle, enthalpies in all states must be calculated using the thermodynamic tables and taking into account the following.

• The pressure of state 1 and 4 are equal

• The pressure of state 2 and 3 are equal

• State 1 is superheated steam

• State 2 is in saturation state

• State 3 is saturated liquid at the lowest pressure

• State 4 is equal to state 3 because the work of the pump is negligible.

Once all enthalpies are found, the following equations are used using the first law of thermodynamics

Wout = m (h1-h2)

Qin = m (h1-h4)

Win = m (h4-h3)

Qout = m (h2-h1)

The efficiency is calculated as the power obtained on the heat that enters

Efficiency = Wout / Qin

Efficiency = (h1-h2) / (h1-h4)

first we calculate the enthalpies in all states

h1=3386kJ/Kg

h2=2073kJ/Kg

h2=h3=167.5kJ/Kg

we use the efficiency ecuation

$Efficiency =\frac{(h1-h2) }{(h1-h4)} =\frac{3386-2073}{3386-167.5} =0.408=40.8%$

8 0

2 years ago

What are some constraints related to size, time, or materials? Remember, constraints are limitations, issues, or obstacles.

Sergeeva-Olga [200]

Answer:

too big, too small, deadlines, not enough materials

Explanation:

4 0

2 years ago

Trade-offs can be necessary at any point in time during the life cycle of a project. It is quite possible, and probable, for the

anastassius [24]

Answer:

According to the Principles of Project management, the three factors which dominate the lifecycle of any project are:

Time;
Cost; and
Performance.

The relationship between the three is usually governed by trade-offs.

Explanation:

In simple term, in executing a project, one must deal with the factors mentioned above.

It is always desirous for a project to be finished within a stipulated time. If the time required is reduced inconsiderably, it will most likely incur more cost and even impact performance.

On the other hand, if the project is cost-sensitive and is executed to a very minimalistic budget, performance will be impacted and it may take a protracted amount of time.

In addition to the above, if the principal decides to change the original design of the project, the performance expected is altered. This will attract additional time as well as cost.

It is possible for any of the above factors to be renegotiated and readjusted at any time during the project. It usually is a trade-off.. that is one for the other.

Cheers!

7 0

3 years ago

A hot-water stream at 60oC enters a mixing chamber with a mass flow rate of 0.5 kg/s where it is mixed with a stream of cold wat

Nezavi [6.7K]

Answer: 0.306 kg/s

Explanation:

If we assume that the specific heat for all stream is constant, we can then say, the mass flow rate of cold water can be calculated by using the energy balance equation.

The energy balance equation basically states that, the heat gained is equal to the heat lost

m'1h1 + m'2h2 = m'3h3

m'1T1 + m'2T2 = (m'1 + m'2) T3

0.5 (60) + m'2(10) = (0.5 + m'2)41

30 + 10m'2 = 20.5 + 41m'2

30 - 20.5 = 41m'2 - 10m'2

9.5 = 31m'2

m'2 = 9.5 / 31

m'2 = 0.306 kg/s

7 0

3 years ago

Read 2 more answers

A W18 X 119 is used as a compression member with one end fixed and the other end pinned. The length is 12 feet. What is the desi

laiz [17]

Answer:

156.0 ksi

Explanation:

The formula of compressive strength is CS = F / A

where F is the force or load while A is the cross-sectional area

Given the inertia Ag = 35.1 in^4 , which is less than 40, the steel has a short column.

E = 29000 ksi

L = 12ft

r = 2.69 in

therefore;

CS = π^2 E / (kL^2/r)^2

= π^2 29000 / (0.8 x 12^2 / 2.69)^2

= 286292.756 / 1834.4089 = 156 ksi

3 0

2 years ago