import tensorflow as tf

from tensorflow.python.framework import graph_util

v1 = tf.Variable(tf.constant(1.0, shape=[1]), name = "v1")

v2 = tf.Variable(tf.constant(2.0, shape=[1]), name = "v2")

result = v1 + v2

init_op = tf.global_variables_initializer()

with tf.Session() as sess:

    sess.run(init_op)

    graph_def = tf.get_default_graph().as_graph_def()

    output_graph_def = graph_util.convert_variables_to_constants(sess, graph_def, ['add'])

    with tf.gfile.GFile("E:\\Saved_model\\combined_model.pb", "wb") as f:

           f.write(output_graph_def.SerializeToString())

from tensorflow.python.platform import gfile

with tf.Session() as sess:

    model_filename = "E:\\Saved_model\\combined_model.pb"

    with gfile.FastGFile(model_filename, 'rb') as f:

        graph_def = tf.GraphDef()

        graph_def.ParseFromString(f.read())

    result = tf.import_graph_def(graph_def, return_elements=["add:0"])

    print(sess.run(result))