using System;

using System.Collections;

using System.Collections.Generic;

​

public class Program

{

    struct specs

    {

        public double length;

        public double temperature;

        public double pressure;

    }

    struct section

    {

        public specs evaptor;

        public specs adia;

        public specs condser;

        public double length => evaptor.length+

                                    adia.length+

                                    condser.length;

    }

​

    public class PHP

    {

        public static void Main()

        {

            List<section> part = new List<section>();

            part.Add(new section()

            {

                evaptor={length=1,temperature=2,pressure=3}, 

                adia={length=4,temperature=5,pressure=6}, 

                condser={length=7,temperature=8,pressure=9}

            });

            foreach (section s in part)

            {

                System.Console.WriteLine($"{s.evaptor.length}, {s.adia.length}, {s.condser.length}, {s.length}" );

            }

        }

    }

}