Consider the implications of for an open system.

1. For an insulated pipe with negligible changes in potential and kinetic energy, positive work done by the fluid flowing in the pipe on the surroundings implies that the enthalpy input is __ (less than, larger than, equal to) the enthalpy output.

2. Saturated liquid water enters a pipe at 212F and leaves the pipe as saturated steam at the same temperature and pressure. In the absence of any kinetic or potential energy changes or any shaft work, Q must be __ (negative, zero, positive).

3. The outlet stream of a process is 100 ft higher than the inlet stream near the earth's surface. If Q, , and are all zero for the process, then Ws must be __ (positive, negative, zero).

4. In the absence of any kinetic or potential energy changes and any work, a process stream undergoing a negative change in H requires that Q be __ (negative, zero, positive).

5. For the process streams entering and exiting a turbine engine powering an aircraft, Ws is (positive, zero, negative).

6. For a typical power plant for which Ws and Q are both negative and for which potential and kinetic energy changes are negligible, must be __ (positive, negative, zero).

+ , + , = Q + W + + , HV HV