The first law of thermodynamics is a formulation of the law of conservation of energy in the context of thermodynamic processes. The law distinguishes two principal forms of energy transfer, heat and thermodynamic work, that modify a thermodynamic system containing a constant amount of matter.

The first law of thermodynamics is actually the law of conservation of energy stated in a form most useful in thermodynamics. The first law gives the relationship between heat transfer, work done, and the change in internal energy of a system.

The time rate of change of energy within a system is expressed dE dt = ˙Q − ˙W. d E d t = Q ˙ − W ˙. In words this equation is: [the time rate of change of energy in a system at time t] = [the net rate of heat transfer into a system at time t] – [the net rate of work out of a system at time t].

Variation of pressure with depth: Apply between two points in the same fluid. Where “below” refers to point at lower elevation and “above” at higher elevation. 1 2 x and x are the initial and final displacements of the spring. During actual exp/comp process of gases, P and V …

Use thermodynamic data tables to identify enthalpy, internal energy, and other thermodynamic properties using system temperatures and pressures. Solve energy balance problems using thermodynamic data. Systems are typically divided into three main categories depending on how the system interacts with its surroundings:

With this convention, we would write “Q + W” in our energy balances. However, historically work has also been defined in physics as positive when work is done by the system on the surroundings. In this other case, the energy balance would be written with “Q – W”.

Energy balance: = ̇− ̇= ̇− ̇+ ̇(h V2 + 2 ) − ̇(h 2 2 ) Based on the assumptions of a. given problem, many terms . 2 2 − 2 2 and − = 0 when changes kinetic and potential energy are assumed to be zero. It is good practice to start every releva. ire equation before cancelling out any terms. Thermal Efficiency: The following table notes three t.

First Law of Thermodynamics - The First Law of Thermodynamics states: Energy can neither be created nor destroyed, only altered in form. For any system, energy transfer is associated with mass and energy crossing the control boundary, external work and/or heat crossing the boundary, and the change of stored energy within the control volume.

The first law of thermodynamics is introduced as a relation between heat transfered, work done and change in the energy content of the system. For a closed system the concept of work is expanded to include boundary work Pdv. For an open system, the concept of flow energy Pv and enthalpy is introduced.

To specify the rates of reactions in a nonisothermal reactor, we require a model to determine the temperature of the reactor, i.e. for the reaction A + B )k*1. k1. C r = k1(T ) cAcBk1(T ) cC. The temperature is determined by the energy balance for the reactor.