-
36 Languages:
2.8 Validation by an Independent Company
2.8.1 Methodology
FVB Energy conducted a validation of the RETScreen CHP model, based on the approach described below.
FVB in-house load calculations were used to compare equivalent full load hour values calculated by the RETScreen CHP module, based on the equations contained in this e-textbook. Process loads and baseloads were set to zero to first compare the core energy calculations, then the same baseload values were added to again compare full load hours calculated.
Heating values of various fuels identified in the user manual were checked against published values. Deviations were flagged.
FVB in house distribution pipe sizing methods were used to calculate pipe sizes for the same loads the RETScreen CHP module was used to calculate pipe sizes.
Steam properties calculated by the RETScreen CHP module were compared to calculated values based on ASME 1999 steam table data.
Steam Turbine performance calculated by the RETScreen CHP module was compared to steam turbine performance using GE Energy process simulation software called GE Enter Gatecycle. This commercially available software establishes design point efficiency and performance for any type of steam turbine based on Spencer Cotton Cannon performance correlations.
Gas turbine performance is represented by the heat rate, published for each individual gas turbine. The heat rate data points presented in the user manual for use by the user to input into the gas turbine performance section of the module were compared to published heat rate information found in the 2003 Gas Turbine World Handbook.
Reciprocating Engine heat rates presented in the user manual for use by the user were compared to the heat rates of engines FVB have been involved in specifying and purchasing for CHP projects in Canada.
FVB’s in-house energy calculation model for CHP systems was used to compare the amount of heat recoverable that the RETScreen CHP module calculated.
Chiller and boiler seasonal efficiency ranges identified in the user manual were compared to efficiency data compiled in the FVB project database.
FVB did not validated the performance of the following systems within the RETScreen CHP module:
FVB Energy conducted a validation of the RETScreen CHP model, based on the approach described below.
FVB in-house load calculations were used to compare equivalent full load hour values calculated by the RETScreen CHP module, based on the equations contained in this e-textbook. Process loads and baseloads were set to zero to first compare the core energy calculations, then the same baseload values were added to again compare full load hours calculated.
Heating values of various fuels identified in the user manual were checked against published values. Deviations were flagged.
FVB in house distribution pipe sizing methods were used to calculate pipe sizes for the same loads the RETScreen CHP module was used to calculate pipe sizes.
Steam properties calculated by the RETScreen CHP module were compared to calculated values based on ASME 1999 steam table data.
Steam Turbine performance calculated by the RETScreen CHP module was compared to steam turbine performance using GE Energy process simulation software called GE Enter Gatecycle. This commercially available software establishes design point efficiency and performance for any type of steam turbine based on Spencer Cotton Cannon performance correlations.
Gas turbine performance is represented by the heat rate, published for each individual gas turbine. The heat rate data points presented in the user manual for use by the user to input into the gas turbine performance section of the module were compared to published heat rate information found in the 2003 Gas Turbine World Handbook.
Reciprocating Engine heat rates presented in the user manual for use by the user were compared to the heat rates of engines FVB have been involved in specifying and purchasing for CHP projects in Canada.
FVB’s in-house energy calculation model for CHP systems was used to compare the amount of heat recoverable that the RETScreen CHP module calculated.
Chiller and boiler seasonal efficiency ranges identified in the user manual were compared to efficiency data compiled in the FVB project database.
FVB did not validated the performance of the following systems within the RETScreen CHP module:
- Geothermal power
- Photovoltaic
- Wind turbine
- Desiccant cooling
- Hydro turbine
2.8.2 Load and energy calculations
The range of heating and cooling energy use values per unit floor area of a building provided in the user manual fall within the majority of heating and cooling customers encountered by FVB on various projects. The range of unit building heating and cooling loads is reasonable for North American type buildings.
The use of weather data to estimate the amount of energy consumed for heating and cooling over the period of a year is an industry accepted method to establish the core energy consumptions. Added to this core consumption is any base energy loads due to ongoing processes occurring in the building and or domestic hot or cold water uses. These base energy loads are typically specific to each building and should be estimated by the user of the RETScreen CHP module. The following two tables compare two Canadian cities and their Equivalent Full Load Hours as calculated by FVB in-house software and the RETScreen CHP module.
The range of heating and cooling energy use values per unit floor area of a building provided in the user manual fall within the majority of heating and cooling customers encountered by FVB on various projects. The range of unit building heating and cooling loads is reasonable for North American type buildings.
The use of weather data to estimate the amount of energy consumed for heating and cooling over the period of a year is an industry accepted method to establish the core energy consumptions. Added to this core consumption is any base energy loads due to ongoing processes occurring in the building and or domestic hot or cold water uses. These base energy loads are typically specific to each building and should be estimated by the user of the RETScreen CHP module. The following two tables compare two Canadian cities and their Equivalent Full Load Hours as calculated by FVB in-house software and the RETScreen CHP module.
Table 14: Comparison of Heating EFLH Calculations
Table 15: Comparison of Cooling EFLH Calculations
The heating EFLH comparison shows good agreement between FVB calculated values and RETScreen CHP module calculated values. The cooling EFLH shows good agreement as well. According to FVB, the values calculated by the RETScreen CHP module for EFLH are reasonable given the use of the module as a CHP screening tool.
2.8.3 Distribution pipe sizing
Various distribution pipe sizes calculated by the RETScreen CHP module were tested to see what the maximum heating and or cooling capacity could be transmitted through the pipe at a design condition of 40°C temperature difference, and 200 Pa/m pressure drop. The comparison is presented in Table 16. A similar comparison is presented in Table 17 for cooling pipes, assuming a 8°C temperature difference and a 200 Pa/m pressure drop.
Various distribution pipe sizes calculated by the RETScreen CHP module were tested to see what the maximum heating and or cooling capacity could be transmitted through the pipe at a design condition of 40°C temperature difference, and 200 Pa/m pressure drop. The comparison is presented in Table 16. A similar comparison is presented in Table 17 for cooling pipes, assuming a 8°C temperature difference and a 200 Pa/m pressure drop.
Table 16: Pipe Heating Capacity in kW at 200 Pa/m and 40°C Delta T
Table 17: Pipe Cooling Capacity in kW at 200 Pa/m and 8.3°C Delta T
The RETScreen CHP model calculated pipe sizes are more conservative than FVB’s for heating, and very similar for cooling. The comparison shows the validity of the pipe sizing calculations in the RETScreen CHP model.
2.8.4 Fuel heating values
The fuel heating content values provided in the user manual were compared to published values.
The fuel analysis calculators for solid and gaseous fuels, found in the Tools worksheet were tested. By entering the analysis for each fuel into the calculators, a HHV was calculated and compared to the published values associated with each analysis. The following table compare the results and show that there is a reasonable agreement between calculated and published values.
The fuel heating content values provided in the user manual were compared to published values.
The fuel analysis calculators for solid and gaseous fuels, found in the Tools worksheet were tested. By entering the analysis for each fuel into the calculators, a HHV was calculated and compared to the published values associated with each analysis. The following table compare the results and show that there is a reasonable agreement between calculated and published values.
Table 18: Fuel Analysis Comparison; MJ/tonne
Ultimate analysis data for the wood fuel was sourced from published analysis found in Babcock and Wilcox Steam Textbook, 40th Edition. Coffee heating values and ultimate analysis was based on FVB project data, and based on actual analysis from CANMET labs. Pure hydrocarbon heating values were obtained from the Gas Processors Society of America (GPSA) data book, 10th Edition.
2.8.5 Reciprocating engine
The industry standard is to quote reciprocating engine heat rates on a lower heating value basis. The heat rates identified in the user manual are representative of the engines that FVB have been involved with on CHP projects. The heat rate figures were assumed to be converted to HHV basis using natural gas as fuel.
The industry standard is to quote reciprocating engine heat rates on a lower heating value basis. The heat rates identified in the user manual are representative of the engines that FVB have been involved with on CHP projects. The heat rate figures were assumed to be converted to HHV basis using natural gas as fuel.
2.8.6 Gas turbine
The industry standard is to quote combustion gas turbine heat rates on a lower heating value basis. The heat rates identified in the user manual are representative of the gas turbine data presented in the publication 2003 Gas Turbine World Handbook. The heat rate figures were assumed to be converted to HHV basis using natural gas as fuel.
The industry standard is to quote combustion gas turbine heat rates on a lower heating value basis. The heat rates identified in the user manual are representative of the gas turbine data presented in the publication 2003 Gas Turbine World Handbook. The heat rate figures were assumed to be converted to HHV basis using natural gas as fuel.
2.8.7 Steam turbine
Steam Turbine simulation software (GE Enter Gatecycle) was used to calculate unit performance in order to compare to the RETScreen CHP module steam turbine performance calculations. The following table compares the results from the two.
Steam Turbine simulation software (GE Enter Gatecycle) was used to calculate unit performance in order to compare to the RETScreen CHP module steam turbine performance calculations. The following table compares the results from the two.
Table 19: Steam Turbine Performance Calculation Comparison
The calculated power output shows very good agreement between the two software performance models.
2.8.8 Chillers
FVB agrees with the efficiency data presented in the user manual. Efficiencies are representative of chillers performance based on FVB experience in North America.
FVB agrees with the efficiency data presented in the user manual. Efficiencies are representative of chillers performance based on FVB experience in North America.
2.8.9 Steam properties
The steam properties calculated by the RETScreen CHP module for a given steam pressure and temperature were compared to the steam properties calculated by the GE Enter GateCycle software for the same conditions. The GE software utilizes the ASME 1999 steam data as the basis for its calculations.
The very good level of agreement that was seen in the steam turbine performance validation is due to the very good agreement in steam properties calculated by both programs.
The steam properties calculated by the RETScreen CHP module for a given steam pressure and temperature were compared to the steam properties calculated by the GE Enter GateCycle software for the same conditions. The GE software utilizes the ASME 1999 steam data as the basis for its calculations.
The very good level of agreement that was seen in the steam turbine performance validation is due to the very good agreement in steam properties calculated by both programs.
2.8.10 CHP system energy allocation
FVB utilized its in-house CHP system model to estimate the amount of recovered heat energy from a CHP project that could be delivered to the consumer over the year. This useful recovered heat energy was compared to the amount calculated by the RETScreen CHP Module.
The following table summarizes the comparison of the two approaches.
FVB utilized its in-house CHP system model to estimate the amount of recovered heat energy from a CHP project that could be delivered to the consumer over the year. This useful recovered heat energy was compared to the amount calculated by the RETScreen CHP Module.
The following table summarizes the comparison of the two approaches.
Table 20: CHP Energy Allocation Comparison
The amount of energy recovered and used compares very well between the two calculation methods. The FVB approach calculates approximately 8.5% more recovered thermal energy than the RETScreen CHP module.
2.8.11 Conclusions
The RETScreen CHP module software, user manual and e-textbook are intended to serve as an initial technical screening tool for users to conceptually assess the technical and financial feasibility of potential CHP projects. Based on the good agreement found between the RETScreen CHP module technical calculations and calculation processes normally utilized by FVB Energy, it is FVB Energy’s opinion that the module will satisfactorily fulfill this purpose.
The RETScreen CHP module software, user manual and e-textbook are intended to serve as an initial technical screening tool for users to conceptually assess the technical and financial feasibility of potential CHP projects. Based on the good agreement found between the RETScreen CHP module technical calculations and calculation processes normally utilized by FVB Energy, it is FVB Energy’s opinion that the module will satisfactorily fulfill this purpose.
