subclassing plant_loop_prm_baseline_condenser_water_temperatures for 90.1-2016 and 2019

lib/openstudio-standards/standards/ashrae_90_1_prm/ashrae_90_1_prm.PlantLoop.rb

@@ -670,4 +670,42 @@ def plant_loop_set_chw_pri_sec_configuration(model)
     pri_sec_config = 'heat_exchanger'
     return pri_sec_config
   end
+
+  # Determine the performance rating method specified
+  # design condenser water temperature, approach, and range
+  #
+  # @param plant_loop [OpenStudio::Model::PlantLoop] the condenser water loop
+  # @param design_oat_wb_c [Double] the design OA wetbulb temperature (C)
+  # @return [Array<Double>] [leaving_cw_t_c, approach_k, range_k]
+  def plant_loop_prm_baseline_condenser_water_temperatures(plant_loop, design_oat_wb_c)
+    design_oat_wb_f = OpenStudio.convert(design_oat_wb_c, 'C', 'F').get
+
+    # G3.1.3.11 - CW supply temp shall be evaluated at 0.4% evaporative design OATwb
+    # per the formulat approach_F = 25.72 - (0.24 * OATwb_F)
+    # 55F <= OATwb <= 90F
+    # Design range = 10F.
+    range_r = 10
+
+    # Limit the OATwb
+    if design_oat_wb_f < 55
+      design_oat_wb_f = 55
+      OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.PlantLoop', "For #{plant_loop.name}, a design OATwb of 55F will be used for sizing the cooling towers because the actual design value is below the limit in G3.1.3.11.")
+    elsif design_oat_wb_f > 90
+      design_oat_wb_f = 90
+      OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.PlantLoop', "For #{plant_loop.name}, a design OATwb of 90F will be used for sizing the cooling towers because the actual design value is above the limit in G3.1.3.11.")
+    end
+
+    # Calculate the approach
+    approach_r = 25.72 - (0.24 * design_oat_wb_f)
+
+    # Calculate the leaving CW temp
+    leaving_cw_t_f = design_oat_wb_f + approach_r
+
+    # Convert to SI units
+    leaving_cw_t_c = OpenStudio.convert(leaving_cw_t_f, 'F', 'C').get
+    approach_k = OpenStudio.convert(approach_r, 'R', 'K').get
+    range_k = OpenStudio.convert(range_r, 'R', 'K').get
+
+    return [leaving_cw_t_c, approach_k, range_k]
+  end
 end