Search and list in a table different types of heat exchanger and feed pump. From this list identify the most suitable type of heat exchanger for boiler and for condenser and the most suitable feed pump.
Specific enthalpy of the refrigerant
The power output from the generator is 1.5kW and the solar energy is incident at 1kW per unit area.
- The specific enthalpy at the entry of the turbine
At the entry of the turbine, the conditions of the refrigerator are 1600kPa at 60.
Checking from the superheated tables, the specific enthalpy at 1600kPa at 60 is given by
- The specific enthalpy at the exit of the turbine
The refrigerant is at a state of a saturated vapor at 35 at the exit of the turbine. Taking the value of specific enthalpy of refrigerant saturated vapor state at 35 from the saturated tables we find
- The specific enthalpy at the entry of the pump
The liquid is in a saturated liquid state at 35. From the saturated tables, the specific enthalpy of refrigerant saturated liquid state at 35 is given by
Also from the tables, the saturated pressure of the refrigerant liquid at the entry of the pump is given by
The specific volume of the refrigerant liquid across the pump is given by
It is also important to note that as long as the pressure across the solar heater is 1600kPa then the pressure of the liquid at the exit of the pump is also 1600kPa.
Therefore, work added by the pump is calculated as follows;
Thus, enthalpy of the refrigerant at the exit of the pump is given by;
- Ideal process paths
- T-s diagram
- H-s diagram
- The electric power output of the generator
The required electric power, Wre is 1.5kW.
Power output of the generator,
- Net electric output power
- Input power of the boiler feed pump
- Rate of heat delivered
- Rate of heat rejection
- Efficiency of conversion
- Unit mass flow rate
- Necessary electrical power input
- Electrical power output of the generator:
- Net electrical output power
Remember that 1.5 kW power is used to pump water and charge the battery
Therefore, net electrical power output is given by;
- Rate of heat delivery
There is a brief contrast in the values calculated here and those calculated in question 2 because there is no assumption of ideal conditions.
- Mass flow rate
- Electrical power input to the boiler pump
- Electrical power output rating of turbo generator
- Necessary solar collector area
- Necessary water flow rate through the condenser
Shell-and-tube heat exchanger
Multistage Centrifugal Pumps
Contact heat exchanger
Multistage High-Pressure Centrifugal Pumps
Open-flow heat exchanger
Plate heat exchanger
The most suitable heat exchange for boiler and condenser is the Shell-and-tube heat exchanger while the most suitable pump is the Multistage High-Pressure Centrifugal Pump (Leong et al., 2012).
Dry bulb temperature
From the psychometric chart, it can be determined that the wet bulb temperature is
Ameel, B., T'Joen, C., De Kerpel, K., De Jaeger, P., Huisseune, H., Van Belleghem, M. and De Paepe, M., 2013. Thermodynamic analysis of energy storage with a liquid air Rankine cycle. Applied Thermal Engineering, 52(1), pp.130-140.
Bao, J. and Zhao, L., 2013. A review of working fluid and expander selections for organic Rankine cycle. Renewable and Sustainable Energy Reviews, 24, pp.325-342.
Leong, K.Y., Saidur, R., Khairulmaini, M., Michael, Z. and Kamyar, A., 2012. Heat transfer and entropy analysis of three different types of heat exchangers operated with nanofluids. International Communications in Heat and Mass Transfer, 39(6), pp.838-843..
Li, K., 2018. Applied thermodynamics: availability method and energy conversion. Routledge.
Wang, J., Yan, Z., Wang, M., Ma, S. and Dai, Y., 2013. Thermodynamic analysis and optimization of an (organic Rankine cycle) ORC using low grade heat source. Energy, 49, pp.356-365.
Wang, M., Wang, J., Zhao, Y., Zhao, P. and Dai, Y., 2013. Thermodynamic analysis and optimization of a solar-driven regenerative organic Rankine cycle (ORC) based on flat-plate solar collectors. Applied Thermal Engineering, 50(1), pp.816-825.