Document 7R3LZ1exEJk4w8OYXny348Qr8

52 CHAPTER 3 fig. 10.... Room Temperature Patterns for Panel-air System with Water-cooled Luminaires uals to temperature deviations from the optimum was in creased considerably over the observed tolerance for systems where all cooling was accomplished with the air supply. The increased tolerance is due partly to the uniform floor-to-ceiling temperature patterns developed with panel systems. Fig. 10 shows the results of placing strings of fine wire thermocouples in. several locations in a water-cooled luminaire panel-air system.14 INSTALLATION COSTS When compared with other types of systems which do not compromise interior conditions, panel-air systems will usually be somewhat higher in cost when considering only the me chanical contract. However, their use frequently will permit a reduction in ceiling space due to the decrease in required duct size, thus producing an overall saving when the struc tural and mechanical costs are considered on a combined baas. It is practicable, for example, to cool a 200.sq ft section of interior floor area of normal general office space using two water lines of in. copper tubing and two 4)^ in. round ducts conveying air at conventional velocities. REFERENCES 1 Walter Sturrock: Effects of artificial lighting (ASHVE Trans actions, VoL 44, 1938, p. 213). 1962 Guide And Data Book 1 J. N. Livermore: Study of actual versus predicted cooling load on an air conditioning system (ASHVE Transactions, Vol. 49, 1943, p. 287). * C. S. Leopold: The mechanism of heat transfer, panel cooling, heat storage (REraiosBATtNo Engineering, July 1947, p. 33). 4 L. F. schutrum and T. C. Min: Cold wall effects in a ceilingpanel-heated room (ASHVETransactions, Vol. 63,1957, p. 187). * F. W. Hutchinson: Influence of gaseous radiation in panel heating (ASHVE Transactions, VoL 53, 1947, p. 285). . G. B. Wilkes and C. M. F. Peterson: Radiation and convec tion from surfaces in various positions (ASHVE Transactions, Vol. 44, 1938, p. 513). I G. V. Parmelee and R. G. Huebscher: Forced convection heat transfer from flat surfaces (ASHVE Transactions, Vol. 53, 1947, p.245). ' T. C. Min, L. F. Schutrum, G. V. Parmelee and John Vouria: Natural convection and radiation in a panel-heated room (ASHAE Transactions. Vol. 62,1956, p. 337). * L. F. Schutrum, John Vouria and T. C. Mb: Preliminary studies of heat removal by a cooled ceiling panel (ASHAE Trans actions, Vol. 61, 1955, p. 95). 10 L. F. Schutrum and T. C. Mb: Lighting aud cooled air effects on panel cooling (ASHAE Transactions, Vol. 64,1958, p. 189). II C. 8. Leopold: Design factors b panel and air cooling systems (ASHAE Transactions, Vol. 57, 1951, p. 61). " C. S. Leopold: Hydraulic analogue for the solution of prob lems of thermal storage; radiation, convection and conduction (ASHAE Transactions, VoL 54, 1948, p. 389}. u C. S. Leopold: The mechanism of heat transfer, panel cool ing, heat storago--Part H--Solar radiation (Refrioeratino Engineering, June 1948, p. 571). u W. F. Spiegel: A water cooled luminaire b a panel-air system (ASHAE Transactions, VoL 64. 1958, p. 351). u B. F. Raber and F. W. Hutchinson: Panel Heating and Cool ing Analyst* (John Wiley A Sons, New York, 1947). BIBLIOGRAPHY D. Cannel, E. Q. Adams and J. C. Forbes: A new means for raintmiaing radiant heat for high level lighting systems (Illumi nating Engineering Society Transactions, July 1939, p. 726). Merl Baker: Effectiveness and temperature requirements for cooling panels removing internal radiation (ASHVE Transac tions, VoL 58, 1952, p. 287). Mm Jacob*. Beat Transfer VoL I. (John Wiley & Sons, New York, 1948). L. M. K. Boelter, V. H. Cherry, H. A. Johnson and R. C. Martinelli: Heat Transfer Notes (University of California Press, Berkeley and Los Angeles, 1946). Cefling panels cool office building (Engineering News Record, January 17, 1952)1 B. F. Baber and F. W. Hutchinson: Panel hasting and cooling performance studies (ASHAE Transactions, Vol. 48, 1942, p. 35). Merl Baker: Removal of internal radiation by cooling panels (ASHAE Transactions, VoL 55,1950, p. 141). J. Tyndall: On radiant heat b relation to the color and chemi cal constitution of bodies (Fragments of Science, Vol. 1, 1892, p. 74). R. H. Heilman: Surface heat transmission (Mechanical Engi neering, VoL 51, 1929, p. 335). G. S. Leopold: Panel cooling application for air conditioning (Journal of tiie Royal Architectural Institute of Canada, November 1953). CHAPTER 4 HEAT PUMP SYSTEMS FOR AIR CONDITIONING Effect of Structure on System Design, Operating Cycles, Equipment Selection, Supplemental Heating, Heating load Estimates, Compressors, Liquid Subcooling Coils, Defrosting and Draining of Coils, Factory Built Unitary Equipment, Controls, Heat Reclaiming Cycle, Operating Cost THE six common heat pump circuits, with respect to the denser (where the heat is supplied by the high temperature beat sources and heat sinks as well as the mediums used refrigerant), valve 1, zone conditioners, and a circulating to supply the heating and cooling effect to the conditioned pump. The cold water circuit consists of the chiller (where heat space, are discussed in Chapter 58 of the 1961 Guide And is taken from the water by the low temperature refrigerant), Data Book. In addition to these basic circuits, there are many other instances, particularly in larger central plant type installa tions, where heating and cooling may be required simul valve 4, exchanger (where heat is taken from the well water), valve 1, and a circulating pump. The refrigerating com pressor is operated to maintain the desired entering water temperature to the condenser. taneously or where cooling and reheat is needed to maintain a specific relationship between temperature and relative, humidity. Various possible heat pump arrangements to ac complish these and other such operating cycles, together with methods of improving the performance of the installa tion, are described and illustrated in this chapter. Similarly, cooling may be exclusively obtained in the cycle of Fig. 1 by opening valves 2 and 3 and closing valves 1 and 4. With this arrangement, the cold water circuit will consist of the chiller (where heat is removed from the water by the low temperature refrigerant), valve 2, zone conditioners, and a circulating pump. The warm water circuit consists of the con EFFECT OF STRUCTURE ON SYSTEM DESIGN denser (which receives the heat from the refrigerant), valve 3, exchanger (where heat is rejected to the well water), valve 2, The trend of modern buildings is to employ double glazed windows and better insulation, as well as to use more andmore internal areas with considerably higher internal heat gab from lights, people, tabulating machines, and other similar heat dissipating equipment. Systems for such build ings are normally required, particularly during mild weather, to furnish heating to the exterior zones and cooling to the interior rones, simultaneously. In many instances these sys tems may have to change daily or even hourly, between the heating and cooling cycle, b order to maintain the required and a circulating pump. The refrigerating compressor is operated to maintain the desired water temperature entering the chiller. During the intermediate season, simultaneous heating and cooling may be provided by a cycle such as shown in Fig. 1, by modulating valves 3 and 4 when valves 1 and 2 are open. Valve 3 is usually adjusted to maintain 110-120 F water in the condenser circuit and valve 4 to maintain 45-50 F in the chiller circuit. The excess heating and cooling effect is wasted to the exchanger which in turn passes it on to the well water. indoor conditions. The heat pump is exceptionally qualified for such applica tions and frequently shows a considerable saving in operating cost over other systems, because of its inherent ability to transfer heat from an interior zone, for instance, where cooling may be desired to the exterior where heating may be needed. ' OPERATING CYCLES Figs. 1, 2 and 3 show three of the several possible operating cycles for simultaneously providing heating and cooling. Fig. 1 illustrates one method of using water as the heat source and tink and as the heating and cooling medium. Similarly, the cycle of Fig. 2 uses air as the heat source and heat sink, and a non-freeze liquid as the heating and cooling medium; In these two designs the compressor, condenser, chiller and all refrigerant piping and accessories can be preassembled at the factory and shipped as a compact unit with a hermetically sealed refrigerant circuit. The compressor, with a fixed re frigerant circuit between the condenser and chiller, is not shown. Also, the various automatic valves and controls "ceded for a particular installation, to obtain a desired per formance, have not been included. ** The cycle shown by Fig. 1 is very flexible and the beating or cooling medium is instantly available at all times. Heating be exclusively provided to the zone conditioners by closing valves 2 and 3 and opening valves 1 and 4. With the valves in these positions, the water will be divided into two separate circuits. The warm water circuit consists of the con INTERMEDIATE CYCLE: VALVES I AMO t OKK AS RE0UIRE& VALVES S ANO 4 MOOULATIM TO MAINTAIN DESIRED WATER TEMPERATURES. * To provide toBuftuneou* hecfmg and cooCctg wtfh flxod refrigerant drew?. n well water can bo supplied dkwetfy to (A* condenser and duffer instead of mdireetfy through the exdianger. fig. 1 .... Water-to-Water Heat Pump Cyde* 53