Steam enters the condenser of a steam power plant at 20kpa and a quality of 95% with a mass flow rate of 20,000kg/h. it is to be cooled by water from a nearby river by circulating water through the tubes within the condenser. to prevent thermal pollution, the river water is not allowed to experience a temperature rise above 10◦c. if the steam is to leave the condenser as saturated liquid at 20kpa, determine the mass rate of the cooling water required.

The mass rate of the cooling water required is:

Explanation:

First, write the energy balance for the condensator: The energy that enters to the equipment is the same that goes out from it; consider that there is no heat transfer to the surroundings and kinetic and potential energy changes are despreciable.

Where w refers to the cooling water and s to the steam flow. Reorganizing,

Write the difference of enthalpy for water as Cp (Tout-Tin):

This equation will let us to calculate the mass rate required. Now, let's get the enthalpy and Cp data. The enthalpies can be read from the steam tables (I attach the tables I used). According to that, and can be calculated as:

.

The Cp of water at 25ºC (which is the expected average temperature for water) is: 4.176 . If the average temperature is actually different, it won't mean a considerable mistake. Also we know that , so let's work with the limit case, which is to calculate the minimum cooling water mass rate required (A higher one will give a lower temperature difference as a result). Finally, replace data:

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relativism has been, in its various guises, both one of the most popular and most reviled philosophical doctrines of our time. defenders see it as a harbinger of tolerance and the only ethical and epistemic stance worthy of the open-minded and tolerant. detractors dismiss it for its alleged incoherence and uncritical intellectual permissiveness. debates about relativism permeate the whole spectrum of philosophical sub-disciplines. from ethics to epistemology, science to religion, political theory to ontology, theories of meaning and even logic, philosophy has felt the need to respond to this heady and seemingly subversive idea. discussions of relativism often also invoke considerations relevant to the very nature and methodology of philosophy and to the division between the so-called “analytic and continental” camps in philosophy. and yet, despite a long history of debate going back to plato and an increasingly large body of writing, it is still difficult to come to an agreed definition of what, at its core, relativism is, and what philosophical import it has. this entry attempts to provide a broad account of the many ways in which “relativism” has been defined, explained, defended and criticized.

explanation:

the answer would be c