Fix cop calculation to changed slope and offset

oemof · Jul 17, 2024 · c95c760 · c95c760
1 parent 87c7760
commit c95c760
Showing 1 changed file with 15 additions and 14 deletions.
diff --git a/workshop/model/solph-offset.ipynb b/workshop/model/solph-offset.ipynb
@@ -8,27 +8,28 @@
     "\n",
     "# oemof-solph model with variable partload efficiency\n",
     "\n",
-    "The final modification in our energy system model is to implement the load dependent variable COP. To do that we can use\n",
-    "the `OffsetConverter`. This component requires different input compared to our previous implementations. Instead of\n",
-    "a conversion factor connecting input with output as shown in eq. {eq}`simple-conversion`, we define a slope and an \n",
-    "offset (eq. {eq}`slope-offset-conversion`). This also changes the overall efficiency value in an interesting way per eq.\n",
-    "{eq}`offset-efficiency`: We have nonlinear efficiency in a linear model. We can visualize the effect in\n",
-    "{numref}`heatpump-offset-converter`. For that we load the TESPy results and plot the compressor power and COP over the\n",
-    "heat production.\n",
+    "The final modification in our energy system model is to implement the load dependent variable COP. To do that we can\n",
+    "use the `OffsetConverter`. This component requires different input compared to our previous implementations. Instead of\n",
+    "a conversion factor connecting input with output as shown in eq. {eq}`simple-conversion`, we define a slope {math}`m`\n",
+    "and a  normed offset {math}`E_0`. By setting the reference to the heat output of the heat pump, the compressor power\n",
+    "can be determined from the slope and the offset following eq. {eq}`slope-offset-conversion`.\n",
+    "This also changes the overall efficiency value in an interesting way per eq. {eq}`offset-efficiency`: We have nonlinear\n",
+    "efficiency in a linear model. We can visualize the effect in {numref}`heatpump-offset-converter`. For that we load the\n",
+    "TESPy results and plot the compressor power and COP over the heat production.\n",
     "\n",
     "```{math}\n",
     ":label: simple-conversion\n",
-    "E_\\text{out} = \\eta \\cdot E_\\text{in}\n",
+    "\\dot E_\\text{in} = \\frac{1}{\\text{COP}} \\cdot \\dot E_\\text{out}\n",
     "```\n",
     "\n",
     "```{math}\n",
     ":label: slope-offset-conversion\n",
-    "E_\\text{out} = E_0 + m \\cdot \\dot E_\\text{in}\n",
+    "\\dot E_\\text{in} = E_0 \\cdot \\dot E_\\text{out,nominal} + m \\cdot \\dot E_\\text{out}\n",
     "```\n",
     "\n",
     "```{math}\n",
     ":label: offset-efficiency\n",
-    "\\eta = \\frac{E_\\text{out}}{E_0 + m \\cdot \\dot E_\\text{in}}\n",
+    "\\text{COP} = \\frac{\\dot E_\\text{out}}{E_0 \\cdot \\dot E_\\text{out,nominal} + m \\cdot \\dot E_\\text{out}}\n",
     "```\n",
     "\n",
     "```{glue:figure} heatpump-offset-converter\n",
@@ -54,11 +55,11 @@
     "\n",
     "example = tespy_coefficients.loc[7]\n",
     "\n",
-    "heat_production_range = np.linspace(0.5, 1) * 9.1e3\n",
-    "compressor_power = (heat_production_range - example.loc[\"offset\"]) / example.loc[\"slope\"]\n",
+    "heat_nominal = 9.1e3\n",
+    "heat_production_range = np.linspace(0.5, 1) * heat_nominal\n",
+    "compressor_power = example.loc[\"offset\"] * heat_nominal + example.loc[\"slope\"] * heat_production_range\n",
     "cop = heat_production_range / compressor_power\n",
     "\n",
-    "\n",
     "fig, ax = plt.subplots(2, sharex=True)\n",
     "\n",
     "ax[0].plot(heat_production_range, compressor_power)\n",
@@ -141,7 +142,7 @@
    "source": [
     "import oemof.solph as solph\n",
     "\n",
-    "hp_thermal_power = 9.1  # kW\n",
+    "hp_thermal_power = heat_nominal / 1e3  # kW\n",
     "\n",
     "slope = input_data[\"slope\"][:-1]\n",
     "offset = input_data[\"offset\"][:-1]\n",