For an ideal Rankine cycle operating between pressures of 30 bar and 0.04 bar, the work output from the turbine is 903 kJ/kg and the work input to the feed pump is 3 kJ/kg. The specific steam consumption is _________________ kg/kW.h (round off to 2 decimal places).

The correct answer is 4.

Step-by-step Explanation:

In an ideal Rankine cycle, the net work output per unit mass of steam circulating in the cycle, denoted as W_net, is the difference between the work output from the turbine (W_T) and the work input required by the feed pump (W_P or W_comp).
Given parameters from the problem:
Turbine work output, W_T = 903 kJ/kg
Feed pump work input, W_P = 3 kJ/kg

First, we calculate the net work output of the cycle per kg of steam:
$$W_{\text{net}}=W_T-W_P$$
Substituting the given values:
$$W_{\text{net}}=903-3=900\text{kJ/kg}$$

Specific steam consumption (SSC) is defined as the mass flow rate of steam required to produce unit power output. It is typically expressed in kg/kW.h.
Since 1 kW.h is equal to 3600 kJ (since 1 kW = 1 kJ/s and 1 hour = 3600 seconds), we convert the power unit using this factor:
$$\text{Specific Steam Consumption (SSC)}=\frac{3600}{W_{\text{net}}}$$

Substituting the value of W_net into the equation:
$$\text{SSC}=\frac{3600}{900}=4\text{kg/kW.h}$$
Thus, the specific steam consumption is 4 kg/kW.h.