General Disclaimer One or more of the Following Statements may affect this Document  This document has been reproduced from the best copy furnished by the organizational source. It is being released in the interest of making available as much information as possible.  This document may contain data, which exceeds the sheet parameters. It was furnished in this condition by the organizational source and is the best copy available.  This document may contain tone-on-tone or color graphs, charts and/or pictures, which have been reproduced in black and white.  This document is paginated as submitted by the original source.  Portions of this document are not fully legible due to the historical nature of some of the material. However, it is the best reproduction available from the original submission. Produced by the NASA Center for Aerospace Information (CASI) DOE /NASA TECHNICAL MEMORANI-LIA! DOE /NASA TM-82442 SOLAR COOLING SYSTEM PERFORMANCE, FRENCHMAN's REEF HOTEL ST. THOMAS, U. S. VIRGIN ISLANDS - FINAL REPORT By Ilaarry Ilarber Solar F:nergy Ppplications Projects NASA-George C. Marsh a ll '-Jaace Flight Center Marshall 4),,.ce Flight Center, Alabama 35812 6 PCxV^ For the U. S. Department of Energy ti' pG^ ^ r ^ 0 cN RE,C'^ F rp^6!` U.S. Department of Energy Solar Energy J41 o. 4 (bASA-TM-81441) 5OLAN COOLING SYSTEM PERFOiMAN L E, FiiENCtOIAN I S 6EEF UUTEL, VIRGIN ISLANDS kinal Report (NA:iA) 15 P dC A01/MF AJ1 LSLL 1JA N81-.i3b 1 1 UIICI A G3/44 4'7t,95 3, REt provided can "13 wink" in the solar water return line to assist the hot water over a structural wall and to the upper tank. All other collectors drain by gravity to the upper tank. The solar subsystem opil ration it, controlled by an Andover Con- trol Sunlogger Solar Controll p r. A pyranometer and temperature, and pressure, and flow raze sensors are installed at selected locations throughout the solar subsystem. A minicomputer in the "Sunlogger" controller acquires data from the sensors, records and integrates the data, and makes programmed decisions. The decisions are implemented by command signals sent to relays and switches, which, in turn, actuates bumps and valves and causes the system to operatcl. The "Sunlogger" can be programmed and data can be acquired by a remote station through a tele- phone link and modems. The Chiller Subsystem c on,,1:•;t,s or two large absorption chillers, pumps, piping, valves, a heat exchanger, and controls. One chiller, designated Chiller #2, is a Carrier Corporation Modal 16JB018 lithium bromide absorpt 3.on chiller nominally rated at 174 tons, and is powered by 10 phi stream generated by waste heat boilers integrated with the diesel. engines exhaust system. The second chiller, designated Chiller #1, is a specially do- signed Zithitun bromide absorption chiller developed by the a E Carrior Corporat ion t o I)o taio(l w i t h i lio v tuns wman I .--; not, r 1, ;o 1.1 1' system. C4111or #1, dv6iI-q I iat ­d tui model SAM 120 by thc Cal'Hol. Corporati'Lon, is nominally rated at 120 tons capacity at tll(^ Frenchman's Reef site conditions and has, ft Coefficient of per- formance (COP) of 0,7. Series chilling is Omployod with the chilled water flowing from the pumpo,, through Chiller #2, through Chiller #1, and then to Vie load. Sea water is used to remove chiller rejected heat. Both chillers can be used at the same tiffic, or separately. When both chillers are employed at the same time, sea water is divided to both machines because of limited sea water availability and pumping capacity. Thermal energy is provided to Chiller #1, the SAM 120, by hot water. The water can be heated by the solar subsystem, by means of steam and a heat exchanger, 0-- a combination of both steam and the solar subsystem. A three-way valve in the hot water lines actuated by the "Sunlogger" controller controls the flow of hot water.to the SAM 120. When the three-way valve is open, hot water flows from the upper tank to the pump, through the heat exchanger, to the SAM 120, and back to the upper tank. When the three-way valve is closed the hot water circulates from pump to heat exchanger, to the SAM 120, and back to the pump, eliminating the solar subsystem from the circuit. A manually controlled bypass line in the circuit provides the capability for increasing or decreasing the amount of water that is cir- culated to and from the upper tank. 6 A proportional valve (,ontrolti the ,!,towii nupply to the heat exchanger, thereby oontrolling the amount of heat added to the hot water. Steam in supplied from boilers at 125 psi, The temperature of 'the, hot water exltintt the SAM 1140 chiller is measured, and if tho tomporatur y dropt, below it "oet" tom- perature, a pneumatic, conLrollor actuate-s the proportional steam valve to permit steam to f low to the heat exchanger. As steam is added, the incoming hot water J9 heated and the exiting water temperature rises until the "set" temperature is reached, Then the controller adjusts the steam flow to maintain tue in- coming water at sufficient temperature to maintain the "set" temperature An the exiting water. Thus, steam can supplement the heat provided by tile Solar Subsystem to the water, or steam can be used as the ^3olo source of heat whenever solar heat is not available such as at night. Instrumentation: Instrumentation for the solar subsystem con- sists of a pyranometer and temperature sensors, pressuro trans- ducers, flowmeters, wattmeters, and liquid level sensors, in- stalled at selected locations throughout the solar subsystem and integrated with the Andover Controls "Sunlogger" solar con-troller. Data are acquired from 48 analog inputs and 8 dis- crete inputs. The I'Sunloggor" controller is programmed to ana- lyze the acquired data and to issue commands which causes the subsystem to operate as specified. The "Sunlogger" is capable of recording instantaneous real-time data, and for converting that data into a daily timo-phased history. Both the instan- g 7 eous data and the daily history aro avai lab lo to a remoto mat ion by U.-;v of a tololillont h co It p I or and collullort, j a I t s a l ophollo I i ll ks . Thero is, no pvrmanont insL111111011 I ILL i011 illvt ',it I od on t li t, 000 I ing uubsyotem. Dat i, Wat, acquired by utili llf", a H'Poci-al portablo in- 6trumentation Oy-Stelli that Utilized temperature t-;onsors,, pressure transducers, sonic flowmetert; and a pyronometor e- ,^nnoctod with a recording minicomputer. Datm from the cooling subsy.r- ,t -it was acquired usitir the portable instrumentation system over ,. G-day period after the, 8AM 120 was installed. 4. SYSTEM OPE'RATION The operating sequence begins in the solar (lay morning; all solar subsystem water stored in the two 2500 gallon tanks. If the, solar tsi"bsystem has boon operating on the previous day, the stored water has been maintained at close to operating temperatures by the insulated tanks. At 7:45 a.m., and with the upper tank temperature loss than 2500F, the "8unlogger" controller "wakes up" the sy-9tom by turning on pumps. The pumps fill the collector arrays at approximately 150 gallons per minuto for 20 minutes. After filling, the pumps stop and the water is hold in the collectors until the temperature reaches 200 0F. At 200 OF the pumps aro started and the water is con- tinuously circulated from collector arrays to upper tank, to lower tank, to pumps, and back to the collectors. When the temperature of the; heated water returning to the upper tank exceeds 215 0F, and the lower tank temperature 8 reaches 210°F, and oyst,em prop ure in over 5 poi, the Xlow of hot water to the SAM 120 chiller is iuitiatod by the "Sunloggur" controller opening the three-way valve in the hot water line to the chiller. The "Sunlogger" controller automatically closes the three-way valve and terminates flow from the upper tank when the temperature of the water in the upper tank fails to exceed the SAM 120 exit water temperature by d°F. The hot water flows from the upper tank to the pumps, to the heat exchanger, to the SAM 120 culler, to the three-way valve, and back to the upper tank where a baffle separates hot water returning from the collectors from the water returning from the chiller. The temperature of the water exiting the chiller and returning to the upper tank will depend on the; chiller load and the heat content and temperature of the solar Heated water. If the exit water temperature drops below the selected "set" temp- erature, the steam valve controller will cause steam to flow to the heat exchanger to sixpplement the solar heat and maintain the exit water temperature at the "set" temperature. In the afternoon when the insoAtion has diminished or during periods of inclement weather when the sun is obscured and the upper tank water temperature drops and fails to exceed the SAM 120 chiller exiting water temperature by 4"F, the "Sunlogger" will close the throe-way valve and terminate the flow of solar heated water to the SAM 120 chiller. Steam then provides the necessary energy to heat the water sufficiently to operate the chiller. At a p.m. Local, time, the " Sunlogger" is programmed 0 i to shut the solar subsystem down, E'leetri ca l power to t ho pumps and the drain--baek valves is cut off, tho spring loadrd drain-back valves open to permit by-pftssing the pumps, and the water in the collectors drain to the two 2500 gallon tanks. Whenever the electrical power fails, or when an over temperature sensor in the collector array senses a temperature in excess of 300°F, the drain-back valves open and the water in the collector arrays drain back to the two 2500 gallon tanks. When power is restored, the "Sunlogger" controller will close the drain--back valves and actuate the pumps to pump water to the collectors providea that the temperature in the collector arrays has not exceeded 300°F. On a clear day the over temperature sensor will normally prevent operation until the next day if power is inter- rupted longer than 30 ninutes. 5. PERFORMANCE CONSTRAINTS After the installation of the solar subsystem in late 1979, both the solar subsystem and cooling subsystem experienced several malfunctions which interrupted operation. However, during those periods of operations between malfunctions the solar subsystem performed consistently and reliably. na.ta was obtained from the solar subsystem and although that data did indicate th. s quality of performance, 'the overall assessment of performance was in- conclusive because no instrumentation was installed in the chil- ler subsystem. Installation of sensors in the chiller subsystem required shutting the system down and cutting holes in the piping for insertion of the sensors. The shutting down of the hotel's s cooling system was considered to be excessively disruptive to the hotel's operation and would impose undue lisc +.^mfort For the guests; and it wan decided to postpone instrumenting the chil- ler subsystem until installation of the new SAM 120 chiller in July, 1981. subsequently, the MSVC developed portable Check-- . out Test Module (CTM) wi t'li its " strap -on" transducers and snesors which did not require penetrating the. subsystem's pip- ing was used. The portable instrumentation system became avail.- able at the time of the installation of the SAM 120 chiller in July, 1983, and was used in conjunction with the Solar Collection Subsystem's "Sunlogger" controller to acquire overall solar coll.ing system performance data. The amount of time available for acquiring the overall system data after installation of the SAM 120 was limited, but the quality of the data was considered to be adequate to develop a realistic analysis of the solar cooling system performance. The bump initially installed circulating; ho ,16* water from the solar subsystem to the chiller was capable of delivering 200 to 420 gallons per minute .Groin the solar tanks to the chiller. Subsequently, that pump failed and a standby pump was brought into operation. The standby p.iLmp used a larger motor and was capable of pumping over 850 gallons per minute ( gpm) through the chiller. By manually opening the bypass line in the system, the flow to aaad from the upper solar t ank was reduced to ap- proximately 550 gpm. Loth the 550 gpm to and from the solar tank, and the 850 gpm through the chiller exceed design flow rates for the solar subsystem and the SAM 120 chiller and tend 1 1 t to degrade the performance of the overall. RUstem. The sit( intends to replace both pumps in the near future with pumpt that produce the flow rates specified for the solar and co( subsystems. While it is concluded that the excessive pumping rates do degrade the performance, no data is °vailable at this time to determine the degree and extent of the performance degradation experienced. In late 1980, several collector modules were found where the transparent plastic film surface had del:aminated from the com- pound parabolic cusp reflectors. Analysis indicated that dark plastic sheeting used to protect the modules during installation created a "green house" effect, and the resultant heat was sufficient to degrade the adhesive between the clear plastic surface and the reflector and produce delaminiation. The Sun- master Corporation developed a repair kit that consisted of new reflectors in sections which could be slipped into place over the existing reflectors and bolted into place. The replacement reflector kits fitted and conformed to the shape of the existing reflectors such that no degradation of collector performance has been detected. Installation of the replacement reflector kit was completed in July, 1981 prior to SAM 120 installation. 6. PERFORMANCE SUMMARY The performance of the system was demonstrated at two levels of completion. Initially, only the solar collection subsystem was monitored for performance when the operating interface was with an existing absorption chiller. Subsequently, the total system 12 r was monitored briefly after the existing chiller was replaced by the new SAM 120. On March 19 and 20, .1980, tests were ruts on the Solar Cooling System with the then existing Carrier Corporation chiller model. 16JB018 operating with solar heated water. The auxiliary steam heat was shut off and the chiller operated on solar heated water from 11 a.m, through 4;30 p.m. The following data acquired by the "Sunlogger" controller are compared with design predictions; Predicted Actual Insolation in P1are of Collector Total Insolation Available Energy Collected 1817 BTU/Ft 2 Day 1E105 BTU/Ft2Day* 24.8 million BTU 11.4 million BTU' 8.7 million BTU* Energy Delivered to Chiller 10.5 million BTU 7.8 million BTU Energy Delivered vs. Collected Energy 92% 89.6% Collector Efficiency (Energy Available vs. Energy Collected) 35 Solar Subsystem Efficiency (Energy Available vs. Energy Delivered to Chiller) 31.4% *Part of the day was cloudy. Approximate clear day insolation is 1925 BTU/Ft"' Day and energy collected was 9.5 million BTU. No chiller performance was acquired as there was no instrumen- tation installed on the cooling subsystem at the time of the test. The second series of tests were conducted on the solar and chiller subsystems during August 3 through 9, 1981, after in- stallation of the Carrier SAM 120 chiller. In addition to off- design hot water flow rates discussed earlier, climatic con- ditions were considerably less desirable than for the March, 1980 tests due to sporadic showers and periods of cloudiness interrupting the solar day. The following performance was shown for 12:59 p.m. on August 8, 1981: 14 Insolation 275 BTU/Ft 2 hour Temperature of Water to Collectors 205.8°F Temperature of Water Returning from Collectors 221*F Flow Rate of Water Through Collectors 141 GPM Energy Collected 1.07 Million BTU Temperature Water Entering; Heat Exchanger 207.2°F Temperature Water Leaving Heat Exchanger 21d.8°F Temperature Water Leaving Chiller 20a6.3ol, Flow Rate of Water Through Heat Exchanger and Chiller 85'7 GPM Meat Added by Steam in Heat Exchanger 1.54 Million BTU Heat Provided by Solar .81 Million BTU Total Heat to Chiller 2.35 Million BTU Temperature of Chill Water into Chiller 63.5°F Temperature of Chill Water Leaving Chiller 59.1°F Flow Rate Chilled Water Through Chiller 675 GPM Cooling Load (Energy re- moved from Chill Water by Chiller 1.49 Million BTU Chiller Coefficient of Performance (COP) (Cooling Load vs. Heat added to Chiller) .63 15 Solar Collector Efficiency (Energy Available vs. Energy Collected) 28.90 Solar Subsystem Efficiency (Energy .Available vs. Energy Delivered to Chiller) 21.9% Energy Contributed by Steam to Chiller 65.5% Energy Contributed by Solar to Chiller 34.k% Solar energy and steam heat add to me.ke up the total energy re- quired by the chiller for any set of cooling load conditions. The August, 1.981 data shows that 34.5 percent of the energy to the chiller was contributed by the Solar Subsystem, but only 21.9 percent of the total energy available was delivered to the chiller. The March, 1980 test indicated that 31.4 percent of available solar energy was delivered to the chiller. There- fore, it can be expected that with better climatic conditions and with a hot water pump whose capacity matches the system design flow specifications of 450 GPM, the solar subsystem will deliver more of the available solar energy to the chiller. It is reasonable to expect that with a properly sized hot water pump and a 300 BTU/Ft 2 hour day, collector efficiencies could reach 35 percent, 31 percent of available energy would be de- livered to the chiller, and that solar would contribute up to 48 percent of the chiller energy requirements for a 124 ton load. It is also reasonable to expect the chiller coefficient of performance (COP) to reach 0.7 with the proper pump. 16 w^ . 7. REMARKS The Solar Cooling System at the Frenchman's Reef Resort Notel Operational Test Site is one of the larger solar projects in the development program. Tile size of the project and its location have made it uniquely valuable as a Development pro- ject. The experience derived from the project has contributed to program objectives to demonstrate solar energy as a viable alternate energy source for the nation. It is unfortunate that the solar cooling system was not con- figured with the "design" flow rates and control "set po,nts" when performance measurements of the total system were made. Additional measurements of the total system performance whin operating to "design" specifications may be necessary at some later date to fulfill follow-on program objectives. 17 Fi r 1: F nchman' R f HoB v Inn H l. 1 r CfJOli Te OVA ^+ V kt^ k4 4¢+ Kaf 4i p ^ }^. p^ 1.4 H e..^ ^ w rc,'^ k E ^. pi 1-4 W e; W try ^+ 4^ 0 pq -^ :3c rh co H 1 IH ^ -pro E a () 0 11f^'/ //Cd ^ Fry p 0 4 W F^1 H U C:4> H ^ Ca r,.H 19 ^t 6* x i4 Nt-iN V ^ PA ;I Y ^^/ Y ^ O V ►rN E—o H ^ Ira ^ :^ t W ^11 3 I p ill 'T++ ns ^"+ Vi 19 ^G rA . n rte' o 4'qb N VA 0 F^ :> ;r, t) x r--^ 0 C4 9 0 '' r7 0VU) ;e4 c: ! _^ •-- Hy^ r^t ► t IZXUWAL PAGE IS 20 APPROVAL SOLAR COOLING SYSTEM PERFORMANCE, FRENCHMAN' S REEF HOTEL ST. THOMAS, U. S. VIRGIN ISLANDS _ FINAL REPORT By harry Harbor The information in this report has been reviewed for technical content. Review of any information concerning DcAartment of Defense or nuclear energy activities or programs has been made by the MSFC Security Classification Officer. This report, in its entirety, has 'seen determined to be unclassified. z y am ^ .'7 roo shank, J r. Manager, Solar Energy Applications Projects 21