北京某综合楼空调工程毕业设计全套毕业设计翻译英文

1、Applied Thermal Engineering 27 (2007) 2188 2194/locate/apthermengMicro tri-generation system for indoor air conditioning in the Mediterranean climateHans-Martin Henning a,*, Tullio Pagano b, Stefano Mola c, Edo Wiemkena Fraunhofertitute for Solar Energy Systems ISE, 79100 Freiburg, G

2、ermanyb AMG ENERGIA s.p.a., 90139 Palermo, Italyc Centro Ricerche Fiat, 10043 Orbassno, ItalyReceived 24 February 2005; accepted 25 July 2005aAbstractMediterranean countries show two specic features regarding air conditioning of buildings: a high and growing cooling load and high relative humidity,

3、at least in coastal zones. In this contribution we report on the development of an innovative micro scale tri generation system (power + heating + cooling), equipped with a rotor based desiccant system adapted to the Mediterranean con ditions which receives heat for the desiccant regeneration from a

4、 combined heat and power (CHP) cycle.The paper presents the design of the advanced desiccant air handling unit which uses a high ecient combination of a vapor compression chiller working at a high evaporator temperature and a desiccant wheel (silica gel). The electricity of the chiller is sup plied

5、by the CHP system and the heat to regenerate the desiccant is the waste heat of the CHP. System simulations have been used to optimize the hydraulic design and the operation strategy in order to minimize operation costs and maximize energy savings. Some new component models, e.g. for the advanced de

6、siccant cycle were developed for this purpose. The nal design of the entire system consisting of the CHP system, the vapor compression chiller, the advanced desiccant air handling unit and the load system is described. The load system is composed of an air duct network with induction units and a chi

7、lled water network with fan coilsin the oce rooms.Regarding energy performance results indicate an electricity saving 30% in comparison to state of the art solutions based on conventional technology.2005 Published by Elsevier Ltd.Keywords: Tri generation; Desiccant cooling; Humid climates; Dehumidic

8、ation1. Introductionpurpose is based on heat driven water chillers such as absorption chillers (e.g. with the material pair lithium- bromide water) or adsorption chillers. Water chillers are used in combination with dierent techniques to purge cooling loads from the rooms such as e.g. fan-coil syste

9、ms, chilled ceilings or centralized air handling units (AHU). However, in order to treat latent loads, air has to be cooled below the dew-point when chilled water systems are used. Thereby the air is cooled far below the temperature level needed for comfortable indoor conditions and consequently the

10、 chiller works at a COP lower than if employed for sensible cooling, i.e. temperature control, only.Air-conditioning of buildings is a promising applica- tion of co-generation systems during summer. For this purpose thermally driven equipment to supply cooling driven with the co-generator waste heat

11、 has to be em- ployed. The most widespread technology used for this* Corresponding author.E mail addresses: hans martin.henningise.fraunhofer.de (H. M. Henning), tullio.paganoamg.pa.it (T. Pagano), stefano.molacrf.it (S. Mola).1359 4311/$ see front matter 2005 Published by Elsevier Ltd. doi:10.1016/

12、j.applthermaleng.2005.07.031H. M. Henning et al. / Applied Thermal Engineering 27 (2007) 2188 21942189An alternative to treat latent loads by cooling air be- low the dew-point is the direct treatment of ventilation air in an open sorptive cooling cycle, also referred toas desiccant cooling system.uc

13、h a cycle air dehumid-ication is realized using a sorptive component such as a sorptive wheel. Additionally, a temperature decrease can be achieved by combination of the sorptive dehumidi- cation with either direct, indirect or combined (direct + indirect) evaporative cooling.However, the standard d

14、esiccant cooling cycle, whichFig. 1. Standard desiccant cooling system.is fortancetalled in temperate climates like Cen-tral Europe, is not able to cope with the conditions ofwarm and humid climates such as fortance in thecoastal zones of the Mediterranean countries. Thereforeapplication of desiccan

15、t technology uch climates using sorptive rotors requires specic congurations. In the framework of the project MITES (Micro Tri- generation System for Indoor air conditioning in the Mediterranean Climate), a project supported by the European Union, a novel conguration of an open cool- ing cycle based

16、 on sorptive rotor technology has been developed. This heat driven air handling unit receives its driving heat from a motor co-generation unit and is specially designed for weather conditions with high humidity ratios of the ambient air. A pilot system hasbeentalled in fall 2003 at the client buildi

17、ng of thegas utility of the municipality of Palermo (AMG)ic-Fig. 2. Standard desiccant cooling cycle in the T x diagram of humid air.ily/Italy and the system is commissioned and operated with accompanying monitoring during 2004.scheme are typically employed in temperate climates; the example of Fig.

18、 1 is based on typical design condi- tions in Central Europe (e.g. Germany). The air follows the following processes during the system:2. Desiccant air handling unit congurationAs a rst step of the project dierent congurations of desiccant air handling units were compared in order to identify the co

19、nguration which is able to provide de- sired supply air conditions with a minimum of energy consumption. However, before the dierent new designs are presented and compared, the standard desiccant cycle as used in temperate climates is described in detail in order to show the general operation princi

20、ple. Based on this cycle dierent modications were made in order1 ! 2 sorptive dehumidication of supply air; the process is almost adiabatic and the air is heated by the adsorption heat and the hot matrix of the wheel coming from the regeneration side;2 ! 3 pre-cooling of the supply air in counter-ow

21、 to the return air from the building;3 ! 4 evaporative cooling of the supply air to the desired supply air humidity by means of a humidier;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 the fan;6 ! 7 supply air temper

22、ature and humidity are increased by means of internal loads;7 ! 8 return air from the building is cooled using evaporative cooling close to the saturation line;8 ! 9 the return air is pre-heated in counter-ow to the supply air by means of a high ecient air- to-air heat exchanger, e.g. a heat recover

23、 wheel;to adjust climate.ittothespecicneedsinawarm-humid2.1. Standard desiccant cooling cycleThe standard cycle which is mostly applied today uses rotating desiccant wheels, equipped either with silica gel or lithium-chloride as sorption material. All required components are standard components and

24、have been in use for air-conditioning of buildings or factories since many years.The standard cycle using a desiccant wheel is shown in Fig. 1 and the corresponding states of the air in the cycle are shown in Fig. 2. Systems according to this2190H. M. Henning et al. / Applied Thermal Engineering 27

25、(2007) 2188 21949 ! 10 regeneration heat is provided for means of a co-generation system;tance by10 ! 11 the water bound in the pores of the desiccant material of the dehumidifer wheel is desorbed by the hot air;11 ! 12 exhaust air is blown to the environment bymeans of the return air fan.Applicatio

26、n of the cycle described above is limited to temperate climates. Reason is, that the achievable sup- ply air dehumidication is not high enough to enable di- rect evaporative cooling at conditions with far higher values of the humidity of ambient air.Fig. 4. Cycle of Fig. 3 in the T x diagram of humi

27、d air.3. Cycles adjusted to humid climatestrols the air to achieve the nal desired humidity(air states 3 ! 4). A re-heater (air states 4 ! 5) is needed, if the supply temperature shall enter the room with a comfortable temperature, i.e., a temper- ature not below 18 C.For all studied cycles the same

28、 boundary conditions, i.e., temperature and humidity values of ambient air, supply air to the building, return air from the building and regeneration air to regenerate the sorption material were assumed. These values are shown in Table 1. The following modied cycles which all use cooling coils in ad

29、dition to the sorptive wheel were studied regarding their energy performance:2 ! 3); a scheme is shown in Fig. 5 and the corre- sponding air states in Fig. 6. Using this system the complete dehumidication of ambient air is realized by sorption. A second cooling coil (air states 5 ! 6) is necessary i

30、n order to achieve the desired supply Standard cycle with a cooling coil added behind the heat recovery wheel on the supply air side; a scheme is shown in Fig. 3 and the corresponding air states in Fig. 4. The sorptive wheel realizes a pre-dehumid- ication (air states 1 ! 2) and the cooling coil con

31、-Table 1Boundary conditions for cycle designParameterUnitValueAmbient air temperature Ambient air humidity ratio Supply air temperature (to room) Supply air humidity ratioReturn air temperature (from room) Return air humidity ratioHot water temperature (from COG)Cg/kg Cg/kg Cg/kg C35.025.018.09.026.

32、011.585.0Fig. 5. Cycle with two sorption wheels.cooling coilbehind heatFig. 3. Standard cycle with additional recovery wheel.Fig. 6. Cycle of Fig. 5 in the T x diagram of humid air.H. M. Henning et al. / Applied Thermal Engineering 27 (2007) 2188 21942191air temperature. Two heating coils are necess

33、ary in order to provide regeneration heat for the rst sorp- tive wheel (airstates 9 ! 10) and the second sorptive wheel(airstates 11 ! 12). Sincenodehumidication is realized by cooling air below the dew-point, the required cold water temperature is relatively high.Cycle employing two cooling coils,

34、a rst one in front of the sorptive wheel for pre-dehumidication (air states 1 ! 2) and a second one for control of supply airtemperature(airstates 4 ! 5); ascheme is shown in Fig. 7 and the corresponding air states in Fig. 8. Although pre-dehumidication is realized by cooling the air below the dew-p

35、oint, a high value of chilled water temperature is sucient since the dehumidica- tion takes place at a high value of the humidity ratio and thus at a high saturation temperature of water vapor.At last a conventional system has been modeled in order to compare the sorptive cycles with a reference; a

36、scheme is shown in Fig. 9 and the corresponding air states in Fig. 10. This system consists of a conven- tional air handling unit in which evaporative cooling of the return air is used to pre-cool the ambient air withaheatrecoverysystem(airstates 1 ! 2). Acool- ing coil guarantees that the desired l

37、evel of dehumid- ication is achieved (air states 2 ! 3). A re-heater (airFig. 9. Conventional reference cycle without sorption wheel.Fig. 10. Cycle of Fig. 9 in the T x diagram of humid air.states 3 ! 4) is needed, if the supply temperature shall enter the room with a comfortable temperature, i.e.,

38、a temperature not below 18 C.The calculation of the air states has been carried outusing a design tool developed at the Fraunhoferti-tute for Solar Energy Systems in which many dierentsystem congurations can be studied. The computer toolcontaan overall of 21 components which can beFig. 7. Cycle with

39、 a cooling coil before the sorption wheel.switched on or o in order to derive a new congurationout of the complete system. Standard performance g- ures for all components were used; the used desiccant wheel model has been developed by Motta 1 and is de- scribed in Motta et al. 2. A by-pass fraction

40、of 20% was used for sorptive wheel regeneration, i.e., only 80% of the return air have to be heated up to the regeneration temperature and pass the sorptive wheel.In order to compare the performance of the dierent cycles the following performance gures have been dened: The total cooling, Pcooling,to

41、t is dened as the enthalpy dierence between ambient air and supply air multi- plied with the air mass ow:P cool;tot m_ air hambienthsupplyFig. 8. Cycle of Fig. 7 in the T x diagram of humid air.2192H. M. Henning et al. / Applied Thermal Engineering 27 (2007) 2188 2194The conventional cooling, Pconv

42、denotes the the cool- ing supplied by the cooling coils, for tance using chilled water from a compression chiller.nominal air ow of 1000 m3/h at return air conditions (26 C). The following conclusions can be drawn from this comparison:The standard cycle with additional cooling coil behind the heat r

43、ecovery wheel (scheme of Fig. 3) requires the lowest amount of conventional cooling. However, this cooling is needed at a low temperature level, since the nal humidity control of the supply air is realized with this cooling coil.Both, the 2-wheels cycle (Fig. 5) as well as the 2-cool- ing-coils cycl

44、e (Fig. 7) need chilled water at a far higher temperature. This means that eventually other environmental heat sinks such as well water might be used if available.The 2-wheels cycle requires a far higher amount of regeneration heat than both other sorptive cycles and the highest electricity demand f

45、or the ventilators. The lowest overall electricity demand is shown by the 2-cooling coils cycle and a reduction of electric con- sumption of about 34% in comparison to a conven- tional system (Fig. 9) is achieved.COPchiller,The chiller COP,denotes the COP of aconventional vapor compression chiller a

46、nd depends on the dierence between the temperature of chilledTchilled waterwater,and the temperature of ambientair, which denes the condensation condition of theCOPchillerchiller; to calculate thethe performanceof a typical market available compression chiller employing FKW 134a as refrigerant has b

47、een used. The sorptive cooling, Pcool,sorpt, denes the amount of the total cooling which is not covered by the cooling coils:P cool sorpt; P cool tot Pconv;The sorptive COP, COPsorpt, is dened as the fraction between the sorptive cooling and the required heatfor regeneration of the desiccant,Preg:P

48、cool;sorptCOPsorptPregPel,ventdenes the electricity demand of the ventila-Finally, for thetallation at the client building oftors. This electricity demand depends on the overall pressure drop of the air handling units which is quite dierent for the dierent designs due to the imple-the gas utility of

49、 the municipality of Palermo (AMG) the 2-cooling-coils conguration was selected, although this conguration shows a higher regeneration heat demand compared to the standard conguration.mented components.Pel,chiller is the electricity demand of the chiller which is dened by the fraction between the co

50、nventional cooling and the chiller COP:However, since the amount of waste heat from the co- generation system is far higher than the heat needed by the desiccant system, this is no limiting condition. P conv Pel;chillerCOPchiller4. Design of the complete systemThe total electricity demand, Pel,tot,

51、is the sum of the electric consumption of the chiller and the ventilators:P el;tot P el;chiller P el;ventResults of the comparison of all the performance g- ures dened above for the studied systems are sum-After the design of the desiccant air handling unit the design of the complete system consisti

52、ng of the co-gener- ation unit, the air handling unit, the compression chiller and the building related components has been made, Based on a detailed cooling load calculation it became obvious that not all cooling loads can be covered bymarized in Table 2. All given values referto aTable 2Comparativ

53、e results of the studied system congurationsParameterUnitStandard2 Wheels2 Cooling coilsReferenceFig. 319.111.283.940.62.813.4131.8Fig. 519.112.714.94.356.415.50.410.82.923.7225.6Fig. 719.111.715.14.330.62.683.2834.3Fig. 94.00Scheme shown in Total cooling, Pcool,totCon

54、ventional cooling, Pconv Tchilled waterChiller COP, COPchiller Sorptive cooling, Pcool,sorpt Regeneration heat, Preg Sorptive COP, COPsorptElectricity demand ventilators, Pel,vent Electricity demand chiller, Pel,chiller Total electricity demand, Pel,tot Electricity savingkW kW CkW kW0.34.705.00kW kW

55、 kW%H. M. Henning et al. / Applied Thermal Engineering 27 (2007) 2188 21942193Fig. 11. Scheme of the complete system at the client building of the gas utility of the municipality of Palermo (AMG). The sy stem is used for eld testing and supplies the second oor of the building. Meaning of abbreviatio

56、ns: COG = co generation plant; EHP = electrical heat pump (water chiller, air cooled); AHU = air handling unit with sorptive wheel according to the scheme in Fig. 7; DHS = domestic hot water storage; EHX = heat exchanger for rejection of excess heat.the air handing unit. Therefore a fan coil system

57、is oper- ated in addition which is supplied with chilled water from the compression chiller as well. A scheme of the overall system is show in Fig. 11. Fig. 12 presents a pho-Table 3Energy balance of the complete system design caseParameterUnitValuem3/h kW kW kW kW kW kW kW kW kW110012.812.05.700.663.009.3621.857.9213.93Volume ow fresh air Cooling power for AHU Cooling for fan coils EHP electric demandVentilators electric demand Appliances electric demand Total electric demand CO