const myHeaders = new Headers();
myHeaders.append("X-API-KEY", "YOUR_API_KEY");
myHeaders.append("Content-Type", "application/json");

const raw = JSON.stringify({
  "inputs": {
    "calculationMethod": "Design",
    "selectedFluidSide1": {
      "fluidId": 53,
      "isGas": false,
      "inputValue": null
    },
    "selectedFluidSide2": {
      "fluidId": 53,
      "isGas": false,
      "inputValue": null
    },
    "coCurrent": false,
    "selectedHeatExchangers": [
      {
        "heatExchangerInputType": "Parent",
        "id": 1
      }
    ],
    "heatLoad": {
      "amount": 1500,
      "unit": "HeatLoadUnit.Kilowatt"
    },
    "inletTemperatureSide1": {
      "amount": 80,
      "unit": "TemperatureUnit.DegreeCelsius"
    },
    "inletTemperatureSide2": {
      "amount": 20,
      "unit": "TemperatureUnit.DegreeCelsius"
    },
    "outletTemperatureSide1": {
      "amount": 40,
      "unit": "TemperatureUnit.DegreeCelsius"
    },
    "outletTemperatureSide2": {
      "amount": 50,
      "unit": "TemperatureUnit.DegreeCelsius"
    },
    "flowSide1": null,
    "flowSide2": null,
    "maxPressureDropSide1": {
      "amount": 20000,
      "unit": "PressureUnit.Pascal"
    },
    "maxPressureDropSide2": {
      "amount": 20000,
      "unit": "PressureUnit.Pascal"
    },
    "numberOfPasses": null,
    "numberOfPlates": null,
    "numberOfPlatesStack1": null,
    "numberOfPlatesStack2": null,
    "oversurface": null,
    "portSwitch": true,
    "autoperformance": false
  }
});

const requestOptions = {
  method: "POST",
  headers: myHeaders,
  body: raw,
  redirect: "follow"
};

fetch("https://api.swep.net/calculateSinglePhase", requestOptions)
  .then((response) => response.text())
  .then((result) => console.log(result))
  .catch((error) => console.error(error));