Desiccant HVAC system driven by a micro-CHP: Experimental analysis

Energy and Buildings 42 (2010) 2028–2035

Contents lists available at ScienceDirect

Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild

Desiccant HVAC system driven by a micro-CHP: Experimental analysis Giovanni Angrisani a , Francesco Minichiello b , Carlo Roselli a,∗ , Maurizio Sasso a a b

Università degli Studi del Sannio, Dipartimento di Ingegneria, Piazza Roma 21, Benevento, 82100, Italy Università degli Studi di Napoli Federico II, DETEC, P.le Tecchio 80, Napoli, 80125, Italy

a r t i c l e

i n f o

Article history: Received 4 August 2009 Received in revised form 22 April 2010 Accepted 20 June 2010 Keywords: Decentralized polygeneration Micro-CHP Desiccant wheel Hybrid HVAC system Experimental analysis

a b s t r a c t In the Mediterranean area, there is increase in demand for summer cooling satisfied by electrically driven units in domestic and small commercial sectors; this involves electric peak loads and black-outs. Consequently, there is an increasing interest in small scale polygeneration systems fuelled by natural gas. In this paper, attention is paid to a test facility, located in Southern Italy, to carry out experimental analysis on a small scale polygeneration system based on a natural gas-fired Micro-CHP and a desiccant HVAC system. The MCHP provides thermal power, recovered from engine cooling and exhaust gas, for the regeneration of the desiccant wheel and electric power for the chiller, the auxiliaries and the external units (computers, lights, etc.). The HVAC system can also operate in traditional way, by interacting with electric grid and gas-fired boiler. An overview of the main experimental results is shown, considering both the desiccant wheel and the global polygeneration system. The experimental results confirm that the performances of the desiccant wheel are strongly influenced by outdoor thermal-hygrometric air properties and regeneration temperature. The polygeneration system guarantees primary energy savings up to 21.2% and greenhouse-gas emissions reductions up to 38.6% with respect to conventional HVAC systems based on separate energy “production”. © 2010 Elsevier B.V. All rights reserved.

1. Introduction In order to obtain dehumidification, in a conventional air conditioning system, air is usually cooled below the dew point by means of a coil interacting with an electric compression chiller. Subsequently, it is heated up to desired supply temperature. This is the so-called “cooling dehumidification”, or “mechanical dehumidification”. In a desiccant assisted system, moist air is dehumidified by means of a desiccant wheel (DW), increasing overall system energy efficiency by avoiding overcooling air and reheating, as well as precluding oversized capacity to meet dehumidification load. The process air stream flows through the desiccant material (such as silica gel, activated alumina, lithium chloride salt, or molecular sieves) that retains the moisture of the air. The desiccant capacity of this material can be restored through its regeneration via a hot air stream, usually heated by a gas-fired boiler. The process air stream, exiting the wheel, is then cooled to desired supply temperature, for example by the cooling coil of an electric chiller. The main advantages of this system, in comparison with conventional electric driven HVAC one, are [1,2]:

∗ Corresponding author. Tel.: +39 0824 305577/6; fax: +39 0824 325246. E-mail address: [email protected] (C. Roselli). 0378-7788/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.enbuild.2010.06.011

- sensible and latent loads can be controlled separately; - the chiller is smaller and operates at a small temperature lift with a greater COP; - process air reheating is avoided; - consistent energy savings can be obtained; - humidity and IAQ (Indoor Air Quality) control is better; - environmental impact can be reduced.

The disadvantage of this technology is higher investment cost. The waste heat of a small cogeneration plant can be used effectively to regenerate the desiccant material, while the cogenerator electricity can drive a chiller or an electric heat pump (EHP) to meet the room sensible load. In [3] the results of a simulation model, carried out to design an experimental hybrid HVAC system, are reported. The test facility is located in the South of Italy, in a humid town. A microcogenerator supplies electric energy to an EHP and other electric devices. Waste heat recovered from the MCHP is utilized to regenerate the DW. Possible excess of thermal energy can be used to produce domestic hot water. In [4,5] a hybrid HVAC system energetically matched to a MCHP is analyzed. The test facility is set in Hamburg, Germany. The system is characterized by a radiant floor cooling which interacts with borehole heat exchangers and balances the sensible load of the room. Thermal energy obtained from the MCHP, at a temperature between 55 and 65 ◦ C, is used to heat the regeneration air, while electric energy supplied by the

G. Angrisani et al. / Energy and Buildings 42 (2010) 2028–2035

2029

Nomenclature AHU AS CHP COP CO2 CS DW E EHP HVAC IAQ LHV MCCHP MCHP P PES re rt T

air handling unit alternative system combined heat and power coefficient of performance carbon dioxide equivalent emissions (kg/h) conventional system desiccant wheel energy (kWh) electric heat pump heating ventilation and air conditioning indoor air quality lower heating value (kWh/Nm3 ) micro combined cooling heat and power micro combined heat and power power (kW) primary energy saving (%) electric energy share provided to the chiller (–) thermal energy share provided to the desiccant wheel (–) temperature (◦ C)

Greek letters CO2 equivalent CO2 avoided emissions (%) ω air humidity ratio difference (g/kg)  efficiency ω air humidity ratio (g/kg) Subscripts co cooling el electric p primary th thermal Superscripts AS alternative system B boiler CH chiller CS conventional system EG electric grid US user

Fig. 1. Outdoor air temperature and humidity ratio during the tests.

the desiccant cooling system are also evaluated and compared with those of a conventional system. The dehumidification of air can also be achieved by means of a liquid desiccant system. Typically a LiCl–water solution is sprayed in a conditioning chamber, the absorber, so that it comes in contact with the air to be dehumidified. The solution concentration is restored by spraying part of it in a regeneration section, while the remainder is recirculated. Regeneration thermal energy can also be derived from cogenerator thermal wastes for liquid desiccant systems [8–11]. In both the case of solid and liquid desiccant systems, thermal energy for regeneration can be obtained by a solar collector system, typically integrated with an auxiliary fossil-fuelled heater [12–15]. In this paper, the main results of tests carried out in an experimental facility located in Benevento (Southern Italy) have been analyzed. The aim of the field tests was to verify the correct running of a desiccant dehumidification based AHU, interacting with a gas fuelled microcogenerator, and to verify the effectiveness of such a system against a “cooling dehumidification”-based conventional AHU. Considering the experimental results obtained in different operating modes, an energy and environmental analysis has been carried out by comparing the hybrid polygeneration system (MCCHP: Micro Combined Cooling, Heat and Power) with the conventional HVAC one. 2. Desiccant HVAC system driven by a microcogenerator

MCHP powers the electric devices of the office. This system is compared with other systems, such as a hybrid HVAC system without MCHP and a conventional HVAC system, in terms of annual primary energy requirement. In [6], a hybrid air conditioning system incorporating enginedriven chiller and desiccant dehumidification is experimentally tested to measure the performance of engine-driven chiller and dehumidification capacity. A comparison between theoretically predicted and measured values is presented. The waste heat recovered from engine-cooling system and exhaust gases is experimentally determined. Also the improvement of performance of the chiller is measured, due to higher temperatures of chilled water (only sensible cooling is needed). Economic benefits of hybrid air conditioning system over conventional electric chiller are calculated for a reference building. The results reveal that more than 30% savings on operation cost can be achieved. In [7], the performance of a desiccant cooling system, regenerated by means of heat recovery from a gas-fired reciprocating internal combustion engine, is evaluated. The system offers sufficient sensible and latent cooling capacities for a wide range of climatic conditions. Energy efficiency and water consumption of

At Sannio University, in Benevento (South Italy), an advanced desiccant air handling unit coupled with a natural gas reciprocating internal combustion cogenerator, to an electric chiller and to a natural gas-fired boiler, is experimentally analyzed. Nominal characteristics of the cogenerator are the following: electric power Pel = 6.0 kW, thermal power Pth = 11.7 kW, electric efficiency el = 28.8%, thermal efficiency th = 56.2%. The air handling unit allows, during summer operation, to process 800 m3 /h of air that achieves the supply conditions for the room (supply air: temperature T = 13–19 ◦ C, humidity ratio ω = 7–11 g/kg). In Fig. 1 temperature and humidity ratio of outdoor air during tests are shown; Benevento reference conditions are reported too (T = 32 ◦ C, ω = 15 g/kg). 2.1. Test facility Fig. 2 presents a photograph of the air handling unit, highlighting the desiccant wheel, the hydraulic pipes which connect the cogenerator, the boiler and the chiller with the corresponding coils inside the AHU, and the aeraulic ducts which realize the suction and the discharge of process, regeneration and cooling air.

2030

G. Angrisani et al. / Energy and Buildings 42 (2010) 2028–2035

Fig. 2. The air handling unit equipped with desiccant wheel.

In Fig. 3, the layout of the test facility is shown. There are three air streams: - process air (green), which, after being dehumidified (1–2), is precooled by interacting with the cooling air stream (2–3) and finally cooled to the desired temperature by a cooling coil (3–4). It is used to maintain thermal and humidity comfort values in the room; - regeneration air (orange), which, after being heated in the heating coil interacting with the MCHP (1–5) and/or heated in the heating coil interacting with the boiler (5–6), is used to regenerate the desiccant wheel (6–7); - cooling air (blue), which, after being cooled by a direct evaporative cooler (1–8), is used to pre-cool process air exiting the desiccant wheel (8–9). All these air streams are entirely drawn from the outdoor (state 1, common to the three air flows), therefore no recirculation is carried out. The position, the measured parameter, the measuring range and finally the accuracy of the instruments are listed too. In Fig. 4, the processes relative to the process air, the regeneration air and the cooling air are reported on a psychrometric chart. The desiccant wheel (weight = 50 kg, diameter = 700 mm, thickness = 440 mm) is filled with silica–gel, a desiccant material that can be effectively regenerated by means of MCHP thermal wastes at low temperatures (60–70 ◦ C). The rotor matrix is composed of alternate layers of smooth and wavy silica-gel sheets and metallic silicate, chemically bound into an inorganic fiber frame. The realized “honeycomb” frame has several advantages, such as the maximization of the superficial contact area, low pressure drops, low weight but high structural durability. The surface exposed to process airflow (60%) and regeneration airflow (40%) has a diameter of about 600 mm because of the metallic frame of the rotor. 2.2. Energy and environmental analysis In Fig. 5, the energy flows of the MCCHP MCHP/HVAC-DW system are reported. The electric power can be split between the chiller and the direct use (lights, appliances, etc.). By means of re parameter (0–1), which stands for the share of the electric energy for the chiller, different operating modes can be considered. The thermal power can also be split between the regeneration of desiccant wheel and direct use (heating, hot water, etc.), by varying rt parameter (0–1), which stands for the thermal energy share dedicated to the DW. Ep is the primary energy input of the MCHP; th and el are thermal and electric efficiency of the MCHP, respectively. The system operates in different modes [16]: - MCHP mode (rt = re = 0). The cogenerator supplies electricity and thermal energy to the end user. The HVAC system does not operate;

- HVAC-DW mode (rt = re = 1). The electric and thermal energies delivered by MCHP are totally used to activate hybrid HVAC system based on the desiccant wheel; - MCHP/HVAC-DW mode (0 < rt < 1, 0 < re < 1). This trigeneration configuration allows to satisfy the end user requirements for electric, heating and cooling energy. In each energy and environmental comparison, two systems are involved: an Alternative System, AS, characterized by the presence of the desiccant based AHU, and a reference system, usually the conventional system or another alternative system. The following systems have been analyzed: • AS I (desiccant based AHU powered by the MCHP): The MCHP supplies electric energy for AHU electric loads (fans, pumps, desiccant wheel, etc.) and thermal energy for regeneration of the desiccant wheel. • AS II (desiccant based AHU powered by the MCHP with additional external devices): This system is similar to the previous one. The only difference is that MCHP electric power output has been increased up to the nominal value to supply external electric devices and to obtain higher values of thermal and mechanical efficiency of the MCHP. • AS III (desiccant based AHU powered by the electric grid and a natural gas-fired boiler): Thermal power for regeneration of the wheel is supplied by a natural gas-fired boiler, while electric power is supplied by the electric grid. In system IIIa in particular the grid powers AHU electric loads and the chiller, while in system IIIb it powers external electric devices too (computers, lights, etc.). • AS IV (desiccant based AHU powered by the MCHP and a natural gas-fired boiler): Thermal power for regeneration of the wheel is partially supplied by a natural gas-fired boiler and partially by the MCHP, which obviously drives the chiller and the AHU electric self consumptions. • AS V (desiccant based AHU served by the MCHP, with additional external loads, and by a gas-fired boiler): This system is basically similar to the previous one. The only difference is that MCHP electric power output has been increased up to the nominal value to supply external electric devices. • CS (conventional system): This is the usually adopted HVAC system, based on the “cooling dehumidification”. External air is cooled under dew point temperature and dehumidified in a cooling coil interacting with an electric chiller powered by the electric grid. Then, it is reheated to the desired temperature in a heating coil interacting with a natural gas-fired boiler. The COP of the air to water chiller in the CS has been estimated on the basis of the secondary fluid temperatures. Considering that the chiller interacting with the desiccant AHU has to balance only the sensible load of the room, while the chiller interacting with the conventional AHU has to balance the latent load too, the latter operates at a higher temperature lift with a smaller COP than the former.

2031

Fig. 3. The test facility layout.

G. Angrisani et al. / Energy and Buildings 42 (2010) 2028–2035

2032

G. Angrisani et al. / Energy and Buildings 42 (2010) 2028–2035

Fig. 4. The processes relative to process air, regeneration air and cooling air, reported on psychrometric chart.

For both alternative and conventional systems the following hypothesis, derived by Italian average conditions, are also assumed: • Electric grid: Efficiency = 46.0%, CO2 equivalent emission = 0.60 kgCO2 /kWhel (“el” refers to the electrical energy supplied by the grid); • Boiler: equivalent emisEfficiency = 85%, CO2 sion = 0.20 kgCO2 /kWhp (“p” refers to the primary energy input of the boiler); LHV (lower heating value) of natural gas = 9.59 kWh/Nm3 . The energy and environmental comparison is carried out on equal useful energy (thermal, electric and cooling) delivered to final users. In particular, in each test, equal thermohygrometric conditions and volumetric flow rate (800 m3 /h) of the supply air for both the alternative and the conventional system have been assumed. As an example, in Fig. 6, the energy flows of AS II and CS are shown. In all tests, thermal energy recovered from the MCHP has been fully US and E US are used for regeneration of the DW, therefore rt = 1. Eel CO electric and cooling energy delivered to final user respectively. EpB B is thermal energy supplied by is boiler primary energy input, Eth CH is electhe boiler, EpEG is electric grid primary energy input and Eel tric energy supplied to the chiller. EpCS and EpAS are primary energy

Fig. 5. Scheme of MCHP/HVAC-DW polygeneration system.

inputs required by the conventional system and the alternative one, respectively. For energy and environmental analysis, two parameters are commonly used, the primary energy saving (PES, Eq. (1)) and the equivalent CO2 avoided emissions (CO2 , Eq. (2)), defined as follows [17]: PES =

EpCS − EpAS

CO2 =

EpCS

× 100

AS COCS 2 − CO2

COCS 2

× 100

(1)

(2)

AS COCS 2 and CO2 are carbon dioxide equivalent emissions of the conventional system and the alternative one.

Fig. 6. Energy flows of alternative system II and conventional system.

G. Angrisani et al. / Energy and Buildings 42 (2010) 2028–2035

2033

Fig. 7. DW dehumidification capacity as a function of outdoor air humidity ratio.

In the following analysis, the two parameters PES and CO2 are characterized by two subscripts, which refer to the systems involved in the comparison: the first subscript refers to the alternative system, the second one refers to the reference system. 3. Results In Mediterranean climate the experimental plant can be conveniently used for the evaluation of the performances of some components of the HVAC system and the complete system. In the following, an overview of the performances of both the desiccant wheel and the global polygeneration system is reported. 3.1. Desiccant wheel To highlight some peculiarities of the desiccant wheel that have to be considered for a correct design of this type of HVAC system, some experimental investigations have been performed. In Fig. 7, the dehumidification capacity of the DW, that is the difference between inlet (outdoor) and outlet humidity ratio, ω, is shown as a function of the outdoor humidity. It is evident that the driving force for the dehumidification process is the difference between outdoor air humidity ratio and water vapor quantity contained in the desiccant wheel. Hence the dehumidification capacity of the wheel increases with outdoor air humidity ratio. Therefore the desiccant based AHU is particularly indicated in warm and humid climates, like the Mediterranean climate [18]. Another variable that affects dehumidification capacity is the regeneration air temperature, Fig. 8. The experimental results confirm that ω increases with the regeneration air temperature, which in turn depends on the energy system that produces hot water. Finally, the quantity and quality (temperature) of the heat regeneration power influence the dehumidification process. A test

Fig. 8. DW dehumidification capacity as a function of regeneration air temperature.

Fig. 9. Average results of energy comparison between alternative systems and conventional one.

has been realized in order to study the saturation process of the desiccant material, silica gel, contained in the rotor, keeping the desiccant wheel in rotation for a total time of 85 min, without regeneration air. The difference in humidity ratio, ω, quickly decreases. It should be noted that all the previously reported tests have been conducted in stationary conditions, that is when hot water supplied by the MCHP reaches and maintains its maximum temperature, in relation to the electric power delivered by the cogenerator. In real operation, however, stationary regime is attained in a certain time, which depends on the outdoor conditions and on the electric power supplied by the cogenerator. During this time, which can last longer than 30 min, regeneration air temperature might not be adequate, so the desiccant material might somehow saturate. 3.2. Energy and environmental comparison About 70 tests have been conducted to characterize the desiccant wheel and the global energy system. Beginning with these tests, an energy and environmental analysis was carried out in order to compare the performance of the systems described in Section 2. For each test, at fixed outdoor and supply air thermalhygrometric properties, the energy consumptions and equivalent CO2 emissions of the AS I-V systems (cfr. Section 2) are based on the experimental results, while for the CS they are based on a numerical analysis. Finally, an energy and environmental analysis was carried out taking into consideration the average values of the performance of the AS and CS systems involved in the comparison. In Fig. 9, the average results of energy comparison between alternative systems and conventional one are reported, while in Fig. 10, the average results of environmental comparison between the same systems are shown. It is possible to note that AS I, AS II and AS III, which are characterized by the presence of the desiccant based HVAC, can ensure energy savings, in comparison with CS, greater than 6.5% and greenhouse-gas avoided emissions, with respect to the usually adopted HVAC system, always greater than 14.6%. The desiccant based AHUs, powered by the boiler and the grid, AS IIIa and AS IIIb, respectively with and without external electric devices, always perform better than the conventional system. So the desiccant dehumidification technology, matched with an electric chiller for sensible cooling only, can autonomously guarantee significant energy (6.5% and 11.7%) and CO2 emissions (14.6% and 20.2%) savings in comparison to the traditional HVAC systems based on cooling dehumidification. These savings increase when the desiccant based AHU is powered by the MCHP, as in AS I and AS II, which always perform better

2034

G. Angrisani et al. / Energy and Buildings 42 (2010) 2028–2035

humidity ratio decreases. In fact, in conventional system, the temperature decrease of the chilled water, produced by the electric chiller to dehumidify the air, causes a strong COP reduction. Consequently, energy consumptions and emissions increase with respect to the system based on desiccant dehumidification. Thus, the desiccant dehumidification technology is particularly indicated for high latent load applications. 4. Conclusions

Fig. 10. Average results of environmental comparison between alternative systems and conventional one.

than the DW based AHUs powered by the separate “production” systems, AS IIIa and AS IIIb. In fact PESI–IIIa and PESII–IIIb are 2.8 and 9.9% respectively, while CO2,I–IIIa and CO2,II–IIIb are 16.7 and 22.4% respectively. Furthermore, PES and CO2 attain their maximum values when the electric power supplied by the MCHP is increased up to its nominal value (6 kW) for the presence of the external electric devices, as in AS II. This system has the best energy and environmental performance, with respect to both the desiccant based HVAC system without MCHP and the conventional system (PESII-CS and CO2,II-CS are 21.2% and 38.6%, respectively). To highlight the influence of MCHP partial load operation mode, Fig. 11 shows PESII–III and CO2,II–III as a function of the electric power supplied by the MCHP (from 3 kW – chiller OFF, to 6 kW – chiller ON). It is possible to confirm that energy savings and avoided emissions of the AS II, with respect to the desiccant based AHU with separate “production”, AS III, increase with electric power output of the MCHP itself. It is well known that DW dehumidification performances are affected by the available regeneration thermal power. To increase regeneration power, a natural gas boiler can operate, with the MCHP at partial, AS IV, or at full load (AS V: electric chiller ON + AHU self consumptions + external electric devices). Experimental results show that the polygeneration systems, only in their best configuration (AS V), can realize energy and environmental advantages, even if negligible. Obviously, the energy and environmental performances of the desiccant based HVAC systems analyzed in this work vary not only with the type of system, as previously described, but also as a function of other operating variables, such as thermohygrometric conditions of outdoor air and supply air. As an example, in [19] it has been shown that PES and CO2 of the desiccant based systems, powered by a MCHP or by separate electric and thermal conversion systems, increase when supply air

Experimental tests have been carried out in a test facility located in Benevento, in Southern Italy, to evaluate energy and environmental performance of a hybrid HVAC system based on desiccant dehumidification. It was observed that the performances of the desiccant wheel are strongly influenced by outdoor air humidity ratio and regeneration temperature. In particular, the DW dehumidification capacity increases in a similar way when these two operating variables increase. As regards the global system, it can be said that a desiccant based AHU, with regeneration by a natural gas boiler, can guarantee tangible savings in terms of primary energy consumption (6.5%) and greenhouse-gas emissions (14.6%) with respect to a conventional system (“cooling dehumidification” + reheating of the supply air) in which electric and thermal energy are respectively provided by the electric grid and a natural gas-fired boiler respectively. PES and CO2 increase (9.0% and 28.6%, respectively) when the regeneration of the desiccant wheel is obtained by the waste heat realized from a microcogenerator, which also supplies electrical energy to power the chiller and the AHU self consumptions. The best energy and environmental results (PES and CO2 equal to 21.2% and 38.6%, respectively) are obtained when the MCHP supplies its maximum electric and thermal power, and when the AHU has to dehumidify very humid outdoor air or when a very low humidity ratio of the supply air is required. It is therefore possible to affirm that desiccant based AHU technology is especially indicated in hot and humid climates, like the Mediterranean climate, and can lead to sensible energy savings and equivalent CO2 emission reductions with respect to conventional air conditioning systems, especially when it is matched to a small scale cogeneration system operating at full load. Energy savings often give rise to economic savings. Therefore, before installing such a system, a careful economic analysis should be conducted to establish if a reasonable value of the pay-back period can be obtained, usually between three and five years for this type of investment. Currently, the first cost of both MCHP and DW does not seem to guarantee an acceptable economic return (less than 7 years). However, it should be noted that there is a great number of subjects involved in the definition of the economic variables concerning this type of energy system, including the institutional sectors and the private sectors (gas utilities, manufacturers, . . .). For example, government grants, together with attractive rates for electricity export to the grid, may significantly encourage MCHP and DW market penetration [20]. Acknowledgement This work has been supported by Italian research project: PRIN 2007, “Theoretical and experimental analysis of small scale polygeneration based on desiccant wheel”. References

Fig. 11. PESII–III and CO2,II–III versus MCHP electric power.

[1] A. Capozzoli, P. Mazzei, F. Minichiello, D. Palma, Hybrid HVAC systems with chemical dehumidification for supermarket applications, Applied Thermal Engineering 26 (2006) 795–805.

G. Angrisani et al. / Energy and Buildings 42 (2010) 2028–2035 [2] M. Ali Mandegari, H. Pahlavanzadeh, Introduction of a new definition for effectiveness of desiccant wheels, Energy 34 (2009) 797–803. [3] H.M. Henning, T. Pagano, S. Mola, E. Wiemken, Micro tri-generation system for indoor air conditioning in the Mediterranean climate, Applied Thermal Engineering 27 (2007) 2188–2194. [4] G. Schmitz, W. Casas, Experiences with a gas driven, desiccant assisted air conditioning system with geothermal energy for an office building, Energy and Buildings 37 (2005) 493–501. [5] G. Schmitz, W. Casas, Experiences with a small gas engine driven desiccant HVAC-system, in: IGRC, Amsterdam, Holland, 5–8 November 2001, 2001. [6] G. Schmitz, C.K. Qin, Engine driven desiccant-assisted hybrid air-conditioning system, in: Proceedings of 23rd World Gas Conference, Amsterdam, Netherlands, June 5–9, 2006. [7] A. Jalalzadeh-Azar, S. Slayzak, R. Judkoff, T. Schaffhauser, R. DeBlasio, Performance assessment of a desiccant cooling system in a CHP application incorporating an IC engine, International Journal of Distributed Energy Resources 1 (2005) 163–184. [8] X.H. Liu, K.C. Geng, B.R. Lin, Y. Jiang, Combined cogeneration and liquiddesiccant system applied in a demonstration building, Energy and Buildings 36 (2004) 945–953. [9] M. Badami, A. Portoraro, Performance analysis of an innovative small-scale trigeneration plant with liquid desiccant cooling system, Energy and Buildings 41 (2009) 1195–1204. [10] R.M. Lazzarin, A. Gasparella, New ideas for energy utilisation in combined heat and power with cooling: I. Principles, Applied Thermal Engineering 4 (1997) 369–384. [11] R.M. Lazzarin, A. Gasparella, New ideas for energy utilisation in combined heat and power with cooling: II. Applications, Applied Thermal Engineering 5 (1997) 479–500. [12] T. Vitte, J. Brau, N. Chatagnon, M. Woloszyn, Proposal for a new hybrid control strategy of a solar desiccant evaporative cooling air handling unit, Energy and Buildings 40 (2008) 896–905.

2035

[13] T. Katejanekarn, S. Kumar, Performance of a solar-regenerated liquid desiccant ventilation pre-conditioning system, Energy and Buildings 40 (2008) 1252–1267. [14] L. Meia, D. Infield, U. Eicker, D. Loveday, V. Fux, Cooling potential of ventilated PV fac¸ade and solar air heaters combined with a desiccant cooling machine, Renewable Energy 31 (2006) 1265–1278. [15] Y. Sukamongkol, S. Chungpaibulpatana, B. Limmeechokchai, P. Sripadungtham, Condenser heat recovery with a PV/T air heating collector to regenerate desiccant for reducing energy use of an air conditioning room, Energy and Buildings 42 (2010) 315–325. [16] R. Possidente, C. Roselli, M. Sasso, S. Sibilio, Analysis of small scale decentralized cogeneration in Southern Italy, in: Proceedings of 1st International Conference & Workshop on Micro-Cogeneration Technologies & Applications, “Micro-Cogen 2008”, Ottawa, Canada, 2008. [17] V. Dorer, A. Weber, Methodologies for the performance assessment of residential cogeneration systems, Report of IEA, ECBCS Annex. 42, ISBN no. 978-0-662-46951-3, 2007. [18] P. Bourdoukan, E. Wurtz, P. Joubert, M. Spérandio, Critical efficiencies of components in desiccant cooling cycles and a comparison between the conventional mode and the recirculation mode, in: Proceedings of ECOS 2008, CracowGliwice, Poland, June 24–27, 2008. [19] G. Angrisani, F. Minichiello, C. Roselli, M. Sasso, G. P. Vanoli, Experimental analysis of a small scale polygeneration system based on a natural gas-fired micro-CHP and a hybrid HVAC system equipped with a desiccant wheel, Proceedings of ECOS 2009, Foz do Iguac¸u, Paranà, Brazil, August 31–September 3, 2009. [20] R. Possidente, C. Roselli, M. Sasso, S. Sibilio, Microcogeneration and polygeneration for building in mild climate, in: Proceeding of 1st International Conference & Workshop on Micro-Cogeneration Technologies & Applications, “Micro-Cogen 2008”, Ottawa, Canada, 2008.