Document e5EDJDqN9gwZ0wLBD6XJK6b7M

W Water chillers. Oil components, 913 construction standards, 912 design, 911 rating, 914 selection requirements, 911 testing, 914 coolers, 703 design criteria, 705 heat transfer, 707 types, 703 cooling towers, 743 atmospheric 744 characteristic, 750 evaluation, 754 hyperbolic, 746 ASHRAE Guide And Data Book 1965 Water (continued) installation, 754 mechanical draft, 745 operation, 754 performance curves, 752-754 selection, 754 quay ponds, 743 theory, 747 water treatment, 755 wood deterioration, 756 drinking coolers, 914 ratings, 916 refrigeration irestema, 915 standards, 916 stream regulators, 916 typec 914 in budding 406 thermodynamic properties, 35-38 vapor barriers, 385, 413 Water-cooled condensers, 683 Water treatment, 233 biological growths, 237 corrosion control, 234 general considerations, 233 scale control. 235 lAngP-lier index, 235, 236 stability index, 235 selection, 238 boilers, 239 closed recirculating systems, 239 once-ihrough systems, 238 open recirculating systems, 238 return condensate systems, 239 Weather data summer, 488--495 winter, 470-477 Welding. 889 Wet-bulb temperature, 30 Wind speeds, 470-477, 482 asagaBs- ! xxtv CHAPTER 1 thermodynamics and refrigeration cycles THERMODYNAMICS: First Law of- Thermodynamics; Second Law of Thermodynamics; Equations of State; COMPRESSION REFRIGERATION CYCLES: The Ideal Bade Vapor Compression Refrigeration Cycle/ The Reversed-Camot Cycle; 77>e Actual Bask Vapor-Compression Refrigeration Cycle; Complex Vapor Compression Refrigeration Cydes; ABSORPTION.......... REFRIGERATION CYCLES: Bask Absorption Refrigeration Cycle; Thermodynamic and Physical Data Required; ' Practical Cycles; Cycle Analysis * THE purpose of this chapter is to discuss the principles of dynamics for a stationary closed system for any process is thermodynamics and the application of these principles stated as: to refrigeration cycles. Part I of the chapter deals with the iQi - AiWt - U, - Ui (1) general laws of thermodynamics. Part II and Part III discuss the two most common methods used in the transfer of thermal where energy, the compression refrigeration cycle,' and the absorp tion refrigeration cycle. A working knowledge of the fundamentals of thermody namics is presumed of the reader, but it may be desirable to consult a recent textbook on the subject. Several recently developed texts are included in References 1-10 at the end of the' chapter.' iQi = the energy transfer to the system due to a temperature difference between the surroundings and the system, while the system changes from the initial state 1 to the final state % Btu. ; - i- U -- internal energy. Btu. iJP* ** work done by the system as it changes from the Initial to the final state, foot pounds. A = the thermal equivalent of work = 1/778, Btu per foot pound. " PART I: THERMODYNAMICS .Hie field of.science concerned with relationships between heat and work, and properties of systems is called thermody In differential form this equation becomes: dQ = dU + AdW and per unit mass: (2) namics. The subject as discussed here is a classical presenta dq * du + Adio (3) tion based on two general laws of nature: the first and second lam of thermodynamics. Although the engineer is primarily interested in thermody Then U-um .(4) namics as a study of macroscopic phenomena, and may limit his study to an empirical science, thermodynamics is actually an extension of conventional mechanics to include tempera ture. By the acceptance of quantum mechanics it is possible to explain many of the phenomena hitherto the subject of inadequate theories, and .to determine many of the properties by calculations, some of which are limiting values. Thermodynamics in its broadest sense includes changes in systems involving ' energy transport in non-equilibrium where' m -- mass of the' system. ti " internal energy per unit mass, Btu per pound. The..,total work iW = fi'dW represents all of the work done by the system on its surroundings. In a system in which the forces exerted on the system are in equilibrium with the forces;exerted by the system accompanied by an increase in volume of the system: : ,., states. However, thermodynamics, as discussed in this chap ter, is limited to a study of equilibrium states and changes of iWt - J , PdV state from one equilibrium state to another.1 A thermodynamic system is a collection of matter, bounded where by surfaces, either teal or imaginary. A system may be closed or open, i.e., mass flow into and out of an open system is per mitted. That portion of the universe contiguous to the outside of the boundaries of the system is known as the surroundings: P = force exerted by the surroundings per unit area on the boundaries of the system, i.e. pressure, pounds per square foot. ... . ... - V " volume of system, cubic feet. x For the open system, the corresponding statement of the first FIRST LAW OF THERMODYNAMICS law in differential form is: .... The first law of thermodynamics is based on the results of experiments that attempted to measure the mechanical equiv alent of heat. These experiments dissipated mechanical work by friction into thermal energy, to demonstrate an equivalence in a cyclic process between energy transport by work and energy transport in the form of heat, independent of the state path that was followed. It was postulated that there existed an internal energy function which would describe stored thermal energy. As a consequence, the first law of thermo- The (oenl respoautnlity (or this chapter b ~i--1 to TC 1.1, Thermo dysainica. dE dQ - AdW +(* + AP^dnu ` (5) where ...... , B =* sum of the potential energy,' kinetic energy, and internal energy of the system, Btu. " sum. of the, potential energy, kinetic energy, and internal energy per unit mass of the fluid crossing the boundary of the system, Btu per pound. dm -- mass now penetrating the boundary of the'system, ,.. pounds. If the system is limited to a angle flow of mass entering and a ngk> flow leaving the system, the properties are'desig-