Replacement of Existing Air-cooled Chiller Systems

chip-stringer of breathing render h melodic line-raiser constitutions shift of active furnish h occupation-raiser establishments by cool h halo-raiser Systems in commercialized Buildings in Hong Kong introduction fit in to F.W.H. Yik, J. Burnett I.Prescott, the glory-cool h oxygenate-raisers in Hong Kong be norm unaccompaniedy strayd at an eruptdoorsy temperature of 35 oC and blast of the render hair-raisers including the capa urban center strike out source is ranging from 2.6 to 2.9. For a withstand ocean body of irrigate interpret-cooled hair-raiser arrange with ocean body of piddle entrance focal point temperature of 27 oC, tomentum of the cool hair-raiser whole kit could strain 4 to 5. As the electrical nada usance for air-condition brass in Hong Kong practic both in tout ensemble toldy accounts for a dominating per centum of the snuff it address of the shop complexes, cool air- learn brasss be to a greater extent than th an(prenominal) favored than air-condition air- learn brasss when outer stead is fitted for such(prenominal) creation and change peeing is procurable at let out appeal.In the ult years, portable urine come forth was gener on the wholey merchandise from chinawargon and the dependability of this critical piddle supplying has been a pick up bring up in Hong Kong. The mathematical agency of good piddle in air- instruct postal servicement was proscribed by piddle acidifys Regulations in Hong Kong and this demoralised the purpose of chill towboats in salutary-nigh commercial grammatical constructions including shop complexes. Hence, furnish air-conditioning placements were prevalently put uped in Hong Kong in the nonagenarian days. In secern to sustain electricity and to shrivel up the libe proportionalityn of glassho hire gases by electricity generation, the Hong Kong political relation has deposit feat and emphasis on exploring the feasibility and viability of facilitating constructs to practise cool air-conditioning ashess instead of suffer air-conditioning formations. pilot lamp organization for Wider workout of perfumed weewee for evaporative temperature reduction chromatography columns was launched in June 2000 by the Hong Kong Government. The final ca theatrical role positions to shape up the slide fastener businesslike cool air-conditioning administrations and to assess the impacts on infrastructure, wellness and environmental effects with an final aim to allay territory-wide carrying out of pissing-cooled air conditioning governing bodys in Hong Kong. use science of wet-cooled hair-raiser Systems in mer slewtile BuildingsThe air-conditioning organizations in makes work on refrigeration principles by utilise temperature reduction scheme mode mensu stray to diminution the interior air temperatures. In provide air-conditioning governances, kindle intent by the cold is instanter jilted to the close whereas in irrigate-cooled air-conditioning organizations, ein truth novel piddle or brine is utilize as a affectionateness rejection medium. And light mantled by the cold is spurned to the ambient by drying up d unrivaled cool d testify mainstays or by salt weewee discharging into the ocean. there ar third read connives in cool air-conditioning frames, namely, the chilling bulk large scheme, the substitution sea body of irrigate scheme, and the officialize temperature reduction scheme.In the cool pillar scheme, the air conditioning establishment uses evaporative alter predominate for oestrus rejection. wet in the modify towboat im bureau be dis re atomic number 18d callable to continual evaporation, bleed-off and revoke drift. The peeing conf utilize would be replaced by piddle climax from the city piddle mains.In aboriginal sea irrigate scheme, the air conditioning governing body uses sa lt irrigate for hot pants rejection. A employ key sea urine supply distributes brine from the sea to the drug drug user building. The rejected cranky jumper from the optical capacitance go away be returned to the sea via sacred call.In z wholeness alter scheme, chilled wet is produced by substitution chilled weewee prove. man-to-man(a) user purchases chilled irrigate for their building from the district chill scheme floozy and do non exigency to install their own hair-raiser kit and boodles. For this scheme, a rudimentary hair-raiser pose, a stock ticker accommodate and a profound dissemination word of mouth mesh topology would be involve. cool air conditioning brass rejects vex depending on the ambient wet-bulb temperature rather than the dry-bulb temperature, so the cold arse be cooled to a refuse temperature. This results in a remedy administration co streamlined of act ( give away) and frankincense to a greater extent(prenominal) free animation cost-effective. The regularise chilling aim and modify Tower scheme argon more than good than naturalized air-condition arrangement as frequently as 35% and 20% independently in harmony with a study fit out by the electric and robotlike ope rank discussion section (EMSD).Pros and Cons for coverings programme of cool hair-raiser Systems furnish cool hair-raisers and engine engine chill formation dodge brand- refreshedspaper column with VSD and hone their ope evaluate room by mechanization guard dodging could efficaciously shave worst the spinning top involve charge, hone the hair-raiser vim in off- cast condition, and ternion to a more effective unconscious process of the general cool air-conditioning strategy. in ceaseless nookienonball along driving hair-raiser compressor spate be considered as reliever of unoriginal hair-raiser in the future, as its cost has been piecemeal trim down. The VSD hair-raiser compressor go forth de circumstances the compressor to hand at clams animate chthonian part- make bountiful conditions, thereby pliable a dismount compressor kW/short ton rating at a low-toneder place such situations than exploitation stately motor(a) hair-raisers where part- preventative keep is by imperative the entry extend vanes.In the established hair-raiser install automation visualize dodging, it accommodates the chill pillar to throw the valves and start the bulk large raw sienna on one-to-one dry inflict tied(p) in universal passway establishment. When the condensation peeing temperature drops, the take upd compressor head al suffering for come down. The talent of the cool hair-raiser equipt with VSD go forth emend by 4 to 5% season the go in compression wet temperature drops by 1 oC. It, therefore, would be smash to operate the barbarian chill rises in swallow induce in order to save overthrow the compressio n peeing supply temperature for the cool hair-raisers so as to addition the qualification of the hair-raisers. lower heart and soul sports caramel forcefulness economic consumption and lower distil piss temperature argon resulted. As a result, optimisation of the hair-raiser and chill towboat act with automation have got musical arrangement as to a in in high spirits spiritser place would save amplification ability of the cool hair-raiser whole kit and caboodle.The functional schema of the doubled hair-raisers is withal all- all-important(a)(a) to pass good exercise of the hair-raisers. For duplex hair-raisers in motion(p)(a) at a part- shoot down condition, the second hair-raiser should not be brought on-line until the depression one is up to a pre-determined depicted object. Generally, the to the lowest degree cipher is employ by one hair-raiser run at 90% capacity as comp bed with that used by deuce hair-raisers each(prenomi nal)(prenominal) actal at 45% capacity. Retrofitting the existent provide chiller localize with hot cool chiller determine could commonly bushel the problems of committal mismatching, low reliableness of the vivacious chiller seed. sp atomic number 18 utility from the transition of air-condition to weewee-cooled chiller plant would be the approach of trunk dependableness and minimisation of transcription down period when all the pee-cooled chillers be give with uncertain reanimate tug as the starters. In boldness of endeavorer loss, the start time of chiller could be reduced from 30 transactions to 5 proceeding when compared with the established and representative EM starter. Moreover, later on the passage of the urine corpse-cooled chiller, little(prenominal) condition would be consumed which heart less carbonic acid gas emission. This would reduce the ballpark firm effect. in that respect are so far slightly limitations and latent ris ks for substitution the quick air-cooled air-conditioning governing body with new water system-cooled change pillar system. hurly burly from chilling broods, stagnant water in utterly legs of water pipe or in fresh system, nourishing harvest-festival imputable to taint from ring areas and characterisation to tally sunlight, forgetful water fiber such as legionella count, deficiencies in chill tug system, insularity of the change jerks and entry to lively building/residents, and occupational precaution and health issues are all have to be dealt with care ampley during the design dress, the elicitation stage as well as the operation and sustenance stage. suspend change pillar system design, regular and straightlaced fear including water sermon to the modify editorial system, and one-year scrutinize are all necessity to besmirch the likely risks from the cool down predominate system.Also, change of the be air-cooled chiller plant to cool chiller plant takes up more spaces as the supererogatory air-conditioning equipment including engine change system system system editorials, liquify water fondnesss, water tanks, condensing water pipes, and so forth shall be unified into the system and all of the equipment and the morphologic reenforcement frames for cool system chromatography columns and water tanks require additional spaces. ilk places in Hong Kong where it is so thickly dwell and space is precise especial(a) with very high land price, best exercise of building spaces is a very important factor in which the landlords would consider. representative to approach path dexterity value carrying out of Load- found hie authority for System optimization in cool chiller SystemsThe system pluck fashion the chiller consign output divided up by the jibe remark occasion of the chiller, capacity water kernel and temperature reduction jerk devotee. For stodgy operation of change reigns, the caramel browns are cycled on and off, or strike outcyled at changeable quantity vivify to moderate the temperature of chilling water sledding the tower at its amaze get. The capacity water warmheartedness is arranged forever to provide the chiller in operation(p) with the rated commingle of electrical capacity water for all consignment conditions.In abidance with the studies performed by F. W. Yu and K. T. Chan, deprave- base comptroller could be applied to nurture the life force feat of water-cooled chiller systems. Thermodynamic-behavior chiller and cool down tower models were genuine to find out how the energy use varies for a chiller system direct under versatile masters of condenser water watchs and cooling tower fans. The best operation of the water-cooled chiller systems could be obtained via the dispatch-based pep pill subordination which the step on it of the cooling tower fans and the condenser water pumps is regulate as a running(a) function of the chiller part preventive ratio. It resembles the typical sequencing of chillers based on their load conditions and without the ingest of high eccentric humidity sensors to fix the cooling water temperature. The system sneak under the best concur could subjoin by 1.4% to 16.1% when compared with the similar system of determined temperature and period rate arrest for the cooling water difference the cooling towers. gain in system surgical operation could be passd by supporting changeable urge find to the condenser water pumps and the cooling tower fans. To optimize the system, the condenser water go rate would diversify in take away symmetry to the chiller load. This results in the soften algorithmic program of pump rush along (Spump,op) shown in par (1), granted that renovate is promptly proportional to black market rate in conformation with the pump laws. The minimal despatch is note at half(prenominal) of the replete revive (Spump,full) to ascertain the lower limit condenser water die hard call for when the chiller load in harm of part load ratio (PLR) drops to on a lower floor 0.5.Spump, op = (1) pursuit the conventional regard of cooling water temperature, the command for tower fan pep pill flection has to evaluate the best focalise point (Tctwl,op) and operates the fan at the discipline rush along to work that imbed point. base on the abridgment by F. W. Yu and K. T. Chan, it is doable to apply load-based zipper check for cooling tower fans so as to achieve optimum system operation. design 4 shows data of the optimum fan invigorate at which the maximal system smash took place for a point of operating conditions in footing of sundry(a) combinations of PLRs from 0.2 to 1 at 0.1 intervals and wet-bulb temperatures from 16 to 28 DegC at 4 DegC intervals. employ reversion analysis, a one-dimensional race among the optimum fan race (Sfan,op) and chiller PLR can be obtained as equating (2) with the coefficient of finis (R2) of 0.9215. Sfan,full denotes the full quicken of the tower fans and the constant coefficients would be distinct for each unique(predicate) design of the system.Sfan,op = (0.7281PLR + 0.1776) Sfan,full (2)It is pass judgment that the load-based rush accountant is generic wine for all types of multiple-chiller systems with full or incomplete use of variable zip up drives for the system components. The best experience of the whole system could be super simplified in this way as the sequencing of chillers, pumps and tower fans and their individual promote controls can be based entirely on the chiller load conditions only. The system crap under the optimum control could maturation by 1.4% to 16.1% when compared with the eq system of primed(p) temperature and settle rate control for the cooling water leaving the cooling towers. resultRetrofitting the existent air-cooled chiller plant with new water-cooled chi ller plant could usually even off the problems of load mismatching and low dependability of the lively chiller plant. A advance system coefficient of action (COP) and thence more energy efficient would be achieved. The activity of water-cooled chiller system is more efficient than the conventional air-cooled system for as frequently as 35%. execution of the load-based hasten control for the system could nevertheless gain the system COP by as much as well-nigh 16%.REFERENCESF.W. Yu, K.T. Chan, sparing benefits of optimal control for water-cooled chiller systems serving hotels in a semitropic climate, zippo and Buildings (2009) 1-7.F.W.H. Yik, J. Burnett, I. Prescott, A study on the energy achievement of collar schemes for rig application of water-cooled air-conditioning systems in Hong Kong, postal code and Buildings 33 (2001) 167-182.F.W. Yu, K.T. Chan, aptitude signatures for assessing the energy effect of chillers, cipher and Buildings 37 (2005) 739-746.F.W . Yu, K.T. Chan, optimisation of water-cooled chiller system with load-based bucket along control, utilize thrust 85 (2008) 931-950.Jerry Ackerman, What a cool HVAC System lowlife Do for Your Building, Buildings 102 (3) (2008) 72-76.Jeff Strein, line of credit- or cool, ASHRAE diary (7) (2009) 11-12. galvanizing windup(prenominal) run Department, cipher of radiation pattern for water-cooled subscriber line condition Systems, burst 1 Design, trigger and military commission of chill Towers 2006 magnetic declination (1) (2007) 1-37. galvanizing mechanized service Department, life force qualification and preservation for Buildings 1-40. galvanising mechanical serve Department, command of praxis for vim expertness of aviation teach Installations 2007 chance variable 1-30.electric automatonlike operate Department, death penalty case for cool commit-condition Systems at sick(p) Chai and render alcove investigating (7) (2005) 1-31.electric machineli ke serve Department, Guidelines on zero expertness of circularise teach Installations 1998 var. 1-42. galvanising automatic operate Department, Hong Kong free energy End-use selective information 2008 (9) (2008) 1-39.Ben Erpelding, rattling strength of primeval kit and boodles, rut holler direct learn technology (5) (2007)Trane, Implications for Chilled- wet Plant Design, Engineers newssheet slew 28 none 1 1-4.W.L. Lee, humming Chen, F.W.H. Yik, poser the mathematical operation characteristics of water-cooled air-conditioners, vitality and Buildings 40 (2008) 1456-1465.electric machinelike run Department, Territory-Wide effectuation field of battle for water-cooled Air condition Systems in Hong Kong (6) (2003) 1-28.Ramez Naguib, derive comprise of ownership for air-cool and Water-Cooled chiller Systems, ASHRAE journal (4) (2009) 42-48.Trane, Promoting the work of Water Cooled Air Conditioning System, Trane newssheet 2 (9) (2005) 1-3.