AbstractMediterranean countries show two specific features regarding air-conditioning of buildings: a high—and growing—cooling loadand high relative humidity, at least in coastal zones. In this contribution we report on the development of an innovative micro scaletri-generation system (power + heating + cooling), equipped with a rotor based desiccant system adapted to theMediterranean con-ditions which receives heat for the desiccant regeneration from a combined heat and power (CHP) cycle.The paper presents the design of the advanced desiccant air handling unit which uses a high efficient combination of a vaporcompression chiller working at a high evaporator temperature and a desiccant wheel (silica gel). The electricity of the chiller is sup-plied by the CHP system and the heat to regenerate the desiccant is the waste heat of the CHP. System simulations have been used tooptimize the hydraulic design and the operation strategy in order to minimize operation costs and maximize energy savings. Somenew component models, e.g. for the advanced desiccant cycle were developed for this purpose. The final design of the entire systemconsisting of the CHP system, the vapor compression chiller, the advanced desiccant air handling unit and the load system isdescribed. The load system is composed of an air duct network with induction units and a chilled water network with fan-coilsin the office rooms.36252
Regarding energy performance results indicate an electricity saving >30% in comparison to state-of-the-art solutions based onconventional technology.  2005 Published by Elsevier Ltd.Keywords: Tri-generation; Desiccant cooling; Humid climates; Dehumidification 1. IntroductionAir-conditioning of buildings is a promising applica-tion of co-generation systems during summer. For thispurpose thermally driven equipment to supply coolingdriven with the co-generator waste heat has to be em-ployed. The most widespread technology used for this purpose is based on heat driven water chillers such asabsorption chillers (e.g. with the material pair lithium-bromide–water) or adsorption chillers. Water chillersare used in combination with different techniques topurge cooling loads from the rooms such as e.g. fan-coilsystems, chilled ceilings or centralized air handling units(AHU). However, in order to treat latent loads, air hasto be cooled below the dew-point when chilled watersystems are used. Thereby the air is cooled far belowthe temperature level needed for comfortable indoorconditions and consequently the chiller works at aCOP lower than if employed for sensible cooling, i.e.temperature control, only. An alternative to treat latent loads by cooling air be-low the dew-point is the direct treatment of ventilationair in an open sorptive cooling cycle, also referred toas desiccant cooling system. In such a cycle air dehumid-ification is realized using a sorptive component such as asorptive wheel. Additionally, a temperature decrease canbe achieved by combination of the sorptive dehumidifi-cation with either direct, indirect or combined (direct +indirect) evaporative cooling.However, the standard desiccant cooling cycle, whichis for instance installed in temperate climates like
Cen-tral Europe, is not able to cope with the conditions ofwarm and humid climates such as for instance in thecoastal zones of the Mediterranean countries. Thereforeapplication of desiccant technology in such climatesusing sorptive rotors requires specific configurations.In the framework of the project MITES (‘‘Micro Tri-generation System for Indoor air conditioning in theMediterranean Climate’’), a project supported by theEuropean Union, a novel configuration of an open cool-ing cycle based on sorptive rotor technology has beendeveloped. This heat driven air handling unit receivesits driving heat from a motor co-generation unit and isspecially designed for weather conditions with highhumidity ratios of the ambient air. A pilot system hasbeen installed in fall 2003 at the client building of thegas utility of the municipality of Palermo (AMG) in Sic-ily/Italy and the system is commissioned and operatedwith accompanying monitoring during 2004.2. Desiccant air handling unit configurationAs a first step of the project different configurationsof desiccant air handling units were compared in orderto identify the configuration which is able to provide de-sired supply air conditions with a minimum of energyconsumption. However, before the different new designsare presented and compared, the standard desiccantcycle as used in temperate climates is described in detailin order to show the general operation principle. Basedon this cycle different modifications were made in orderto adjust it to the specific needs in a warm-humidclimate.2.1. Standard desiccant cooling cycleThe standard cycle which is mostly applied today usesrotating desiccant wheels, equipped either with silica gelor lithium-chloride as sorption material. All requiredcomponents are standard components and have beenin use for air-conditioning of buildings or factories sincemany years.The standard cycle using a desiccant wheel is shownin Fig. 1 and the corresponding states of the air in thecycle are shown in Fig. 2. Systems according to this scheme are typically employed in temperate climates;the example of Fig. 1 is based on typical design condi-tions in Central Europe (e.g. Germany). The air followsthe following processes during the system:1 ! 2 sorptive dehumidification of supply air; theprocess is almost adiabatic and the air is heatedby the adsorption heat and the hot matrix ofthe wheel coming from the regeneration side;2 ! 3 pre-cooling of the supply air in counter-flow tothe return air from the building;3 ! 4 evaporative cooling of the supply air to thedesired supply air humidity by means of ahumidifier;4 ! 5 the heating coil is used only in the heating sea-son for pre-heating of air;5 ! 6 a small temperature increase is caused by thefan;6 ! 7 supply air temperature and humidity areincreased by means of internal loads;7 ! 8 return air from the building is cooled usingevaporative cooling close to the saturation line;8 ! 热电冷联产户式空调系统英文文献和中文翻译:http://www.youerw.com/fanyi/lunwen_34613.html