What is the exergy destruction?

Exergy destruction is a measure of resource degradation. Although exergy efficiency measures the quality of exergy the system is harnessing, exergy destruction ratio is assessing the degraded resources and specifies the elements in the system where destruction is occurring.

What is exergy rate?

xout is the exergy rate in product or material and Cexout is the associated cost of exergy of the output stream (material, product, etc.). From: Integrated Energy Systems for Multigeneration, 2020.

What causes exergy destruction?

In contrast, exergy is always destroyed when a process is irreversible, for example loss of heat to the environment (see Second Law of Thermodynamics). This destruction is proportional to the entropy increase of the system together with its surroundings (see Entropy production).

How do you calculate exergy efficiency?

1988) that the exergy efficiency of the system on the whole can be calculated as the ratio of total useful exergy effect of the system (product) to available exergy (fuel).

How can exergy destruction be reduced?

The higher the pressure ratio with its design ratio, the more irreversibilities are affected by the gas cycle. By keeping low pressures, although not less than a specific range, we can reduce the destruction rate of exergy.

What is the difference between energy and exergy?

The main important difference between energy and exergy: energy is conserved, while exergy, a measure of energy quality or work potential, can be consumed. The first two terms on the left-hand side of Eq.

Is Exergy efficiency higher than energy efficiency?

So the input exergy is a fraction of input energy. Therefore, the exergy efficiency is higher than the energy efficiency.

Is exergy destruction negative?

The value of exergy loss cannot be negative. Exergy decreases due to irreversibilities in the system. If a system undergoes a spontaneous change to the dead state without a device to perform work, then exergy is completely lost.

How do you calculate Exergy efficiency of a refrigerator?

where ̇ExQ,evap is the thermal exergy rate of the evaporator due to the heat transfer ˙QL from refrigerated space and is calculated as ̇ExQ,evap=˙QL(T0/TL−1) .

What is the formula for exergy destroyed?

Exergy stored in the tank is completely destroyed, I= X des = W rev –W u = W rev 0 Example: X des from a Hot Water Tank When the water is used the X des0can be expressed as: Exergy destroyed, I= X des = W rev –W u = X st –X out Inlet Outlet X st X out Carnot Heat Engine Q H Q Hot Water Tank at T H = 80 Co Environment at T 0 = 10 Co