corrected the formula in Custom Compressor Unit Model notebook (IDAES#64

)

* corrected the formula in Custom Compressor Unit Model notebook

* Revert "corrected the formula in Custom Compressor Unit Model notebook"

This reverts commit 40851a9.

* corrected the formula in Custom Compressor Unit Model notebook

* corrected the formula in Custom Compressor Unit Model notebook

---------

Co-authored-by: Olawale Abimbola <oabimbola@creativeadvtech.com>
Co-authored-by: Andrew Lee <andrew.lee94@gmail.com>

idaes_examples/notebooks/docs/unit_models/custom_unit_models/custom_compressor_doc.ipynb

@@ -36,12 +36,29 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "To demonstrate creation of a new unit model, we will create a constant-heat-capacity ideal-gas isentropic compressor. This will be a simple textbook model. We will utilize the mass and energy balances provided by IDAES control volumes, but we will write our own isentropic constraint based off of equations 7.18 and 7.23 from \"Introduction to Chemical Engineering Thermodynamics\" by J.M. Smith, H.C. Van Ness, and M.M. Abbott. \n",
-    "\n",
-    "The outlet temperature of an ideal gas undergoing isentropic compression is given by \n",
-    "\\begin{align}\n",
-    "& t_{out} = t_{in} + \\frac{1}{\\eta} \\left(t_{in} \\left(\\frac{p_{out}}{p_{in}}\\right)^{\\frac{\\gamma - 1}{\\gamma}} - t_{in}\\right)\n",
-    "\\end{align}\n",
+    "To demonstrate creation of a new unit model, we will create a constant-heat-capacity ideal-gas isentropic compressor. This will be a simple textbook model. We will utilize the mass and energy balances provided by IDAES control volumes, but we will write our own isentropic constraint based off of equations 7.18 and 7.23 from \"Introduction to Chemical Engineering Thermodynamics\" by J.M. Smith, H.C. Van Ness, and M.M. Abbott. "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The outlet temperature of an ideal gas undergoing isentropic compression is given by :"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "$$\n",
+    "t_{out} = t_{in} + \\frac{1}{(\\eta)} \\left(t_{in} \\left( \\frac{p_{out}} {p_{in}} \\right)^{\\frac{\\gamma - 1}{\\gamma}} - t_{in}\\right)\n",
+    "$$"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
     "where $p$ is pressure, $t$ is temperature, and $\\gamma$ is the ratio of constant pressure heat capacity to constant volume heat capacity."
    ]
   },
@@ -309,7 +326,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.12"
+   "version": "3.9.13"
   }
  },
  "nbformat": 4,