def calGasTherCondEq1(params, T):
    """ 
    gas thermal conductivity equation 1 - W/m.K
    args:
        params: 
            equation parameters list [C1, C2, C3, C4]
        T: temperature [K]
    """
    # try/except
    try:
        C1 = params[0]
        C2 = params[1]
        C3 = params[2]
        C4 = params[3]
        _var1 = C1*(T**C2)
        _var2 = 1 + (C3/T) + C4/(T**2)
        _res = _var1/_var2
        return _res
    except Exception as e:
        raise