THEORY AND FIELD PROBLEMS OF THE （理论和现场的问题）.pdf

THEORY AND FIELD PROBLEMS OF THE CAPILLARY TUBE By HENRY EHRENS Sealed Unit Parts CO., Inc. INTRODUCTION that can go wrong with a cap tube, is that it can become restricted or clogged, and it’s always protected by a strainer to prevent this from happening. But the cap tube does become clogged and restricted despite the The capillary or restrictor tube needs no formal introduction strainer, which we will discuss after we look at the theory and principles of to refrigeration service or design engineers. In fact everyone in the cap tubes. refrigeration industry has either heard of, or has had some experience with the cap tube, as we shall call it from no on. Of all the controls used in the refrigeration industry, if we pick out those that are used as pressure reducing devices, we find that they work the same way, in principle, in other industries. For instance, the automatic expansion valve is the same type of control used in reducing the pressure from oxy-acetylene tanks. The same type of valve is also used in water or air reduction. Some of the principles of the thermostatic expansion valve are also used in gas heating controls. But when the cap tube is used in other industries it can only be used as a pressure reducing device, never as a controlling or regulating mechanism. We shall see later on how a fixed length of tubing with a fixed bore can regulate the flow of refrigerant, and