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# 2006 Elsevier B.V. All rights reserved.

main purpose of preheating domestic hot water and/or to cover

air-conditioners has brought great pressure upon energy,

power. The future development trend is building integration

Energy and Buildings 39 (2007with solar energy systems.

Solar cooling systems can be classified into three categories:

namely, solar sorption cooling, solar-related systems and solar-

mechanical systems, thereinto, the former two systems are* Corresponding author. Tel.: +86 21 62933250; fax: +86 21 62933250.

E-mail address: rzwang@mail.sjtu.edu.cn (R.Z. Wang).

0378-7788/$ see front matter # 2006 Elsevier B.V. All rights reserved.doi:10.1016/j.enbuild.2006.11.010for conventional energy. Solar energy therefore has an

important role to play in the building energy system.

The ways solar systems are used in newer buildings usually

combine several solar-related technologies. They may be both

solar heated/cooled, and solar PV powered, i.e. they are simply

solar buildings [2]. Recently, solar water collectors have

undergone a rapid development; they are installed with the

it not only makes the best use of solar energy, but also converts

low-grade energy (solar energy) into high-grade energy for

comfort. In addition, it is meaningful for the energy

conservation and environment protection. Solar cooling has

been shown to be technically feasible. It is particularly an

attractive application for solar energy, because of the near

coincidence of peak cooling loads with the available solarexpenditure and improve thermal comfort. Solar energy is

abundant and clean; it is meaningful to substitute solar energyelectricity and environment. Consequently, solar-powered

air-conditioning system would be a perfect scheme becauserenewable energy systems, which can minimize the energyKeywords: Solar energy; Heating; Air-conditioning; Natural ventilation; Green building

1. Introduction

The modern comfort living conditions are achieved at the

cost of vast energy resources. Global warming and ozone

depletion and the escalating costs of fossil fuels over the last

few yeas, have forced governments and engineers to re-examine

the whole approach to the design and control of building energy

system [1]. Consequently, it is of great importance in the

building field to reconsider the building structure and exploit

a fraction of the space heating demand. However, this

application mainly for obtaining hot water through solar

energy is not very consistent with the order of nature. In winter,

it is convenient to combine hot water system with space heating

system just through increasing the collector area. Whereas, for

summer with high solar radiant intensity and high ambient air

temperature, the demand for air-conditioning and refrigeration

is in preference to hot water, this phenomenon is obvious

especially in the south of China for example. The prevalence ofSolar integrated energy s

X.Q. Zhai, R.Z. Wang *, Y.J.

Institute of Refrigeration & Cryogenics, Shang

Received 29 June 2006; received in revised form

Abstract

Shanghai is characteristic of subtropical monsoonal climate with th

above 4470 MJ/m2 with approximately 2000 h of sunshine. A solar en

supply has been built in Shanghai Research Institute of Building Science

chillers, floor radiation heating pipes, finned tube heat exchangers and a

cooling in summer, natural ventilation in spring and autumn, hot wat

controlled by an industrial control computer and operates automatically

heating capacity is up to 25.04 kW in winter, the average refrigerati

ventilation air flow rate doubles in transitional seasons. The experiment

cooling-based air-conditioning system. After 1-year operation, it is con

space for the weather conditions of Shanghai.tem for a green building

ai, J.Y. Wu, Y.X. Xu, Q. Ma

Jiao Tong University, Shanghai 200030, China

November 2006; accepted 26 November 2006

ean annual temperature of 17.6 8C, and receives annual total radiationsystem capable of heating, cooling, natural ventilation and hot water

e systemmainly contains 150 m2 solar collector arrays, two adsorption

water storage tank of 2.5 m3 in volume. It is used for heating in winter,

upply in all the year for 460 m2 building area. The whole system is

der typical weather condition of Shanghai, it is found that the average

output reaches 15.31 kW in summer and the solar-enhanced natural

vestigation validated the practical effective operation of the adsorption

ed that the solar system contributes 70% total energy of the involved

www.elsevier.com/locate/enbuild

) 985993

Bubased upon solar thermal utilization and the latter one utilizes a

solar-powered prime mover to drive a conventional air-

conditioning system. The solar-powered prime mover can be

either a Rankine engine or an electric motor based on solar

photovoltaic principle. It is reported that the photovoltaic

panels have a low field efficiency of about 1015%, depending

on the type of cells used, which result in low overall efficiencies

for the system [3]. Besides, at otherwise identical refrigerating

output, the solar-mechanical systems are 45 times more

expensive than those powered by solar thermal utilization [4].

Therefore, the majority of solar-powered air-conditioning

systems at present are solar sorption and solar-related systems

based on solar thermal utilization. In most of the solar cooling

systems, hot water driven single-stage lithium bromide

absorption chillers were commonly used. Evacuated tubes or

other high-grade solar collectors were adopted to provide a hot

Nomenclature

COP coefficient of performance

I solar radiant intensity (W/m2)

T temperature (8C)

Greek symbol

h instantaneous efficiency of solar collector arrays

Subscripts

a ambient

chill chilled water

co cooling water

hp heat pipe evacuated tubular solar collector array

hw hot water

in inlet

o outlet

U U-type evacuated tubular solar collector array

X.Q. Zhai et al. / Energy and986water temperature of 8890 8C as a heat source to drive thechiller. Experimental data on the performance of such systems

were reported by several researchers [5,6]. Although a large

potential market exists for this technology, existing solar

cooling systems are not competitive with electricity-driven or

gas-fired air-conditioning systems. The major problems facing

solar absorption cooling systems are its high initial cost, low

system performance, and solar energy usage for only a short

period during 1-day operation [7].

Another potential solar-powered air-conditioning system is

solar adsorption cooling system. It is a better choice to use

adsorption cooling technology for mini type solar-powered air-

conditioning systems [7]. Up to now, the solar-powered

adsorption systems have mostly been intermittent and used

only for ice making application. For applications such as air-

conditioning, when the chilled water temperature requirement

is only around 68 8C, two or more adsorption beds can be usedto produce a cooling effect continuously. Numerical simula-

tions have been done to investigate the performance of a solar

powered air-conditioning system driven by simple flat plate

solar collectors [8]. As for working pairs, a silica gel/wateradsorption refrigerator uses waste heat at below 100 8C, whichwould be suitable for a wider range of solar thermal collector

types [9].

In this paper, an integrated system of heating, air-

conditioning, natural ventilation and hot water supply based

on solar energy, which was designed for the green building of

Shanghai institute of architecture science, was introduced in

detail. The design scheme, operation modes as well as

experimental results were discussed.

2. Integrated solar energy system and the green

building

2.1. Integration of solar collectors and green building

Shanghai is characteristic of subtropical monsoonal climate

with the mean annual temperature of 17.6 8C, and receivesannual total radiation above 4470 MJ/m2 with approximately

2000 h of sunshine. The green building of Shanghai Research

Institute of Building Science is situated in Xinzhuang, which is a

burgeoning town of Shanghai. As a demonstration project, the

green building containsmultiple green energy technologies, such

as solar thermal technology, solar photovoltaic, natural ventila-

tion, natural lighting, indoor virescence, and the like. Here, we

designed an integrated solar energy system for heating, air-

conditioning, natural ventilation and hot water supply. As the

power to drive adsorption chillers and the heat source for the floor

heating and natural ventilation, the solar collectors are the most

important parts. We installed 150 m2 solar collectors on the roof

of the green building, wherein U-type evacuated tubular solar

collectors with CPC of area 90 m2 were placed on the west side

(SCW), and the other 60 m2 heat pipe evacuated tubular solar

collectors on the east side (SCE). For the purpose of efficient

utilization of solar energy, the architects designed a steel

structure roof, facing due south and tilted at an angle of 408 to theground surface, on which the solar collectors were mounted and

integrated with the building perfectly. Fig. 1 shows the

appearance of the green building integratedwith solar collectors.

All solar collectors of both sides were divided into three parallel

rows, as shown in Fig. 2. The collector units in each row were

connected in a series arrangement for the purpose of obtaining

hot water with relatively high temperature, which plays an

important part in improving performance of the solar energy

system. Such an arrangement of solar collectors not only

guarantees high system performance but also improves the

beauty of the building facade. Besides, it provides a feasible idea

for integration of solar collectors and civil buildings especially

for public buildings.

2.2. Design of solar-powered integrated energy system

An integrated energy system based on solar thermal

technologies was designed and set up for building area of

460 m2. As an office building, the hot water demand is not as

significant as that in residential buildings. So, the solar-powered

integrated system design of the green building is mainly

ildings 39 (2007) 985993focused on floor heating in winter and air-conditioning in

summer. Another novel design is natural ventilation enhanced

by solar hot water, which is effective and necessary to solve the

problem of surplus hot water in transitional seasons. Moreover,

it provides a new method for the design of solar-enhanced

natural ventilation.

The system design was based on the calculation results of

Shanghai Research Institute of Building Science. The cooling

det

(2)

(3)

me

con

Fig. 1. The external appearance of the green building integrated with solar

collectors. (For interpretation of the reference to color in this figure legend, the

reader is referred to the web version of the article.)

X.Q. Zhai et al. / Energy and BuFig. 2. Arrangement of solar collector arrays. (a) Heat pipe evacuated tubular

solar collector arrays. (b) U-type pipe evacuated tubular solar collector arrays.(3) In transitional seasons, solar hot water is pumped into

finned tube heat exchangers to induce stack pressure, which

is capable of improving natural ventilation.

(4) The system can be used to supply hot water as long as a heat

exchanger is installed in parallel with whatmentioned above.

2.2.2. Adsorption chiller

In order to complete the solar-powered air-conditioning

system, we choose the environment friendly silica-gel/water as(2) I

stheing rooms realize dry operating mode.

n winter, solar-powered floor heating system is used to

atisfy heating load of the green building.loads independently, and the fan coils inside air-condition-air-conditioning system deals with cooling and humidityand 70%, respectively.

2.2.1. Flow diagram of the integrated solar energy system

Except for solar collectors, the integrated solar energy system

mainly includes two adsorption chillers, floor heating pipes,

finned tube heat exchangers, circulating pumps and a cooling

tower. Besides, a hot water storage tank of 2.5 m3 in volume is

employed to collect solar heat, thereby providing hot water for

the integrated solar energy system. All components are

connected by tubes and valves to form the whole circulating

system. Theflowdiagramof the integrated solar energy system is

shown in Fig. 3, whereAD1andAD2are two adsorption chillers,

CT is a cooling tower, WT is a hot water storage tank, P1 and P2

are two solar collecting pumps, P3 andP4 are hotwater pumpand

cooling water pump, respectively. Through valves located on the

pipes, the integrated solar energy system can be switched to

different operating modes according to different seasons:

(1) In summer, the sensible cooling load is met by solar-

adsorption air-conditioning system, which is discussed in

this paper. The latent cooling load is taken on by a liquid-

desiccant system, which is constructed by Shanghai

Research Institute of Building Science. Thereby, the hybridthe s

solar650 W/m and 450 W/m , respectively.

The average solar collecting efficiency is 40%.

The COP of solar-powered adsorption chiller is 0.4.

It is obvious that 150 m2 solar collectors are capable of

eting the heating and cooling of the system under design

dition. Based on the weather statistic data of Shanghai and

imulation soft ware developed for this project [10], the

fraction in winter and summer was predicted to be 50%(1) The design solar radiant intensity in summer and winter is2 2exprting load in winter. The design performance data were

ermined according to our previous experiments, and

essed as following:desig

heater is 25 kW. The solar integrated energy system was

ned to deal with sensible cooling load in summer andload of air-conditioning area under design condition is 60 kW,

thereinto, 15 kW is sensible cooling load, and the other 45 kW

is latent cooling load. For the same area, the heating load in

win

ildings 39 (2007) 985993 987working pair and invent an adsorption chiller, which is

capable of working from 55 8C to 95 8C. Fig. 4 shows the photoof the silica gel-water adsorption chiller. Owing to its

practicability in low temperature, the chiller is testified to be

suitable for solar-powered air-conditioning system. The

performance test shows that the chiller attains rated refrigerat-

process. Chilled water is cooled down in the methanol chamber

directly. This design idea has made two water evaporators

(Evaporator 1, Evaporator 2) integrated into one methanol

evaporator. Table 1 lists the main performance indices of the

adsorption chiller.

2.2.3. Floor heating pipe

Floor heating systems are becoming increasing popular due

to the fact that they may provide a more comfortable indoor

Fig. 3. The flow diagram of the integrated solar energy system, showing different operating modes: floor radiation heating (FH), natural ventilation enhanced by solar

hot water (NV), air-conditioning (AC).

X.Q. Zhai et al. / Energy and Buildings 39 (2007) 985993988ing capacity of 8.5 kW when the hot water temperature is

85 8C, and the corresponding COP is 0.4.Fig. 5 shows the structure of the silica gel-water adsorption

chiller. This silica gel-water adsorption chiller is composed of

three working vacuum chambers including two desorption/

adsorption chambers and one heat pipe working chamber. In the

adsorption chamber, water is taken as the refrigerant, while in

the heat pipeworking chamber, methanol is used as theworking

substance.

The evaporation cooling in evaporator 1 or 2 is transferred to

the methanol chamber via heat pipe evaporation/condensationFig. 4. The photo of the silica gel-water adsorption chiller.Fig. 5. Schematic diagram of the heat pipe type silica gel-water adsorption

chiller.

Table 1

Main performance indices of the adsorption chiller

Performance of the adsorption chiller Performance index Unit

Refrigerating output 8.5 kW

Outlet temperature of chilled water 10 8CFlow rate of chilled water 1.5 t/h

Inlet temperature of cooling water 32 8CFlow rate of cooling water 5 t/h

Inlet temperature of hot water 85 8CFlow rate of hot water 3.6 t/h

Working pressure of chilled water system 0.6 MPa

Working pressure of cooling water system 0.6 MPa

Working pressure of hot water system 0.6 MPa

Weight in operation 1.5 T

Power supply 2F220 V50 Hz

X.Q. Zhai et al. / Energy and Buenvironment than convective heating systems. Generally, the

supply water temperature of floor heating system is relatively

lower, which leads to the feasibility of low-grade heat source.

As a result, solar energy is suitable for floor heating system. In

this project, we chose cuprotherm floor heating system

produced by Wieland Ltd. of Shanghai. The floor heating coil

pipes are made of high-quality pure copper with the dimension

of F12 0.7 mm, as shown in Fig. 6. They were fixed on the30-mm thick polystyrene insulation layer with spacing interval

200 mm. And then crushed stone concrete was poured with the

thickness of 70 mm. Fig. 7 shows the arrangement of floor

heating coil pipes.

2.2.4. Finned tube heat exchanger

Fig. 6. The photo of floor heating coil pipe.There is an air channel under the roof of the green building,

which is designed by architects for indoor air exhaust through

natural ventilation. In order to enhance natural ventilation by

stack pressure, we installed seven groups of heat exchange

elements inside the air channel. Each group consists of three

Fig. 7. Arrangement of floor heating coil pipe integrated with floor.parallel finned tube heat exchangers as shown in Fig. 8. The

finned tube heat exchanger is made of a 3-m long copper tube

with 540 square fins. The diameter of the tube is 20 mm and

the sectional dimension of the square fins is 102 mm 102 mm.

2.2.5. Data acquisition and control system

The whole system is controlled by an industrial control

computer and operates automatically. The temperatures are

recorded by platinum resistance thermometers, which are

fixed at main points of the system either for inspection or for

control. The flow rate is measured by revolving flowmeter.

Besides, an actinometer is used to measure solar radiant

intensity. The data were recorded at every 15 s interval in a

data logger, which is connected to the industrial control

computer.

3. Performance of solar-powered integrated system

3.1. Instantaneous efficiency of solar collector arrays

Fig. 8. Finned tube heat exchanger inside air channel.

ildings 39 (2007) 985993 989In this system, the operation of solar collecting pump is

controlled by the temperature difference between solar

collectors and the hot water storage tank. Consequently, the

collected solar heat is extracted whenever it is available. The

two solar collector arrays were tested on the efficiency

characteristics under identical weather conditions to evaluate

their respective performance. The instantaneous experimental

collector efficiency data were expressed as the function of

(Tin Ta)/I. It is well known that the transmittance of glassvaries with solar incident angle. The data corresponding to

noon were used. The efficiency for the two solar collector

arrays can be respectively denoted as:

For heat pipe evacuated tubular solar collector array:

hhp 0:65 2:94T in Ta=I (1)For U-type evacuated tubular solar collector array:

hU 0:45 1:10T in Ta=I (2)

Fig. 9. Variations of ambient temperature and solar radiant intensity.

Fig. 11. Variation of heating capacity.

X.Q. Zhai et al. / Energy and Buildings 39 (2007) 985993990whole operation. It is seen that the solar floor heating system

operates continuously for about 12 h with average supply and

backwater temperature of 51.17 8Cand 44.68 8C, respectively.where Tin and Ta are respectively inlet temperature of solar

water heating collector and air temperature, I is the solar radiant

intensity (W/m2).

3.2. Floor radiation heating performance

After hot water in the storage tank is heated to 40 8C, thefloor heating pump is switched on to circulate hot water

between the storage tank and copper pipes underneath the floor

surface until the temperature of hot water in the storage tank

decreases below 30 8C. Fig. 9 shows variations of ambienttemperature and solar radiant intensity under representative

weather condition of Shanghai. It can be concluded that daily

solar radiation and average ambient temperature are 18 MJ/m2

and 1.98 8C, respectively. Fig. 10 shows variations of supplywater temperature and back water temperature during theFig. 10. Variations of supply water temperature and back water temperature

during the whole operation.Also can be seen is that, initially, both supply water

temperature and back water temperature go up, and then fall

off, which is in accord with the variation of solar insolation.

Correspondingly, the heating capacity has similar trend as

shown inFig. 11. The average heating capacity is 21.74 kWin the

whole operation, and it attains 25.04 kW during the working

hours from 9:00 to 17:00, which is sufficient to keep indoor

thermal environment. As a result, the heating floor temperature

and air temperature reaches 23.71 8C and 17.10 8C, respectively,which is higher than those of non-heating room by 16.10 8C and9.16 8C, respectively, as shown in Fig. 12.

The solar-powered floor radiation heating system has been in

operation in sunny days and cloudy days from Dec. 1st, 2004 to

Mar. 13th, 2005. With respect to the whole heating period, the

floor heating system was capable of meeting heating

requirement in 58 days. Experimental results based on these

58 days are listed in Table 2. It is concluded that the solar

fraction is 56%, which agrees well with the predicted value with

the relative error of 10.7%.Fig. 12. Variations of all-day temperatures in floor heating room and non-

heating room.

3.3. Air-conditioning performance

Since the adsorption refrigerating is characteristic of

periodicity and variable behavior, we optimize the operating

mode by maintaining half a periodic time between two

refrigerating output exceeds 20 kW. As for solar-powered air-

conditioning system, it is significant to reduce power

consumption; consequently, electric COP is another important

index to evaluate performance of the system. In this system,

taking two solar collecting pumps (P1 and P2), hot water pump

(P3) and cooling water pump (P4) into account, the whole

power consumption is 1.87 kW, and then the electric COP

averages at 8.19 during 8-h operation, and the maximum

exceeds 10.

From June to August in 2005, the solar-powered air-

conditioning system along with the liquid-desiccant system

Table 2

Summarization of solar-powered floor heating experiments

Month/year

(mm/yy)

Average ambient

temperature (8C)Daily solar

insolation (MJ/m2)

Solar collecting

efficiency (%)

Heating

capacity (kW)

Floor

temperature (8C)Indoor

temperature (8C)

12/2004 12.12 13.04 39.5 22.7 23.43 17.63

01/2005 3.39 14.41 40.6 24.6 20.91 13.19

02/2005 2.97 15.76 38.7 26.3 22.83 14.14

03/2005 8.26 16.68 41.0 27.8 24.02 16.69

X.Q. Zhai et al. / Energy and Buildings 39 (2007) 985993 991adsorption chillers. Thereafter, the whole system realizes stable

operation by the balance of heat consumption and refrigerating

output. Fig. 13 shows variations of ambient temperature and

solar radiant intensity under representativeweather condition of

Shanghai. It is deduced that daily solar insolation and average

ambient temperature are 20.36 MJ/m2 and 31.66 8C, respec-tively. Experimental results show that the air-conditioning

system operates efficiently for 8 h from 9:00 to 17:00. Fig. 14

shows the variations of inlet and outlet temperatures of hot

water, cooling water and chilled water during system operation,

where Thw,in and Thw,o are inlet and outlet temperature of hot

water, respectively, correspondingly, Tco,in and Tco,o for cooling

water, and Tchill,in and Tchill,o for chilled water. During

operation, the average hot water temperature is 70.24 8C andthe maximum value reaches 75.58 8C at 13:00. Besides, theaverage outlet temperature of chilled water is 18.48 8C, whichis suitable for dry operating mode of the air-conditioning

system. Also can be seen is that the chilled water temperature

difference between inlet and outlet averages at 3.53 8C.Fig. 15 shows variation of refrigerating output. It is seen that

the system yields average refrigerating output of 15.31 kW

during the whole operation, which satisfies design standard.

With regard to heat consumption of two adsorption chillers, the

average system COP is 0.35, and average solar COP is 0.15

concerning daily solar insolation. Moreover, the maximalFig. 13. Variation of ambient temperature and solar radiant intensity.Fig. 14. Variations of inlet and outlet temperatures of hot water, cooling water

and chilled water during system operation.Fig. 15. Variation of refrigerating output.

have continuously run in working hour (9:0017:00) of the

green building. Experimental results of three months are

summarized in Table 3. It is concluded that average

refrigeration capacity is 10.76 kW. Accordingly, the average

system COP and average solar COP is 0.32 and 0.12,

respectively. Solar fraction for the system in summer

attains 72% corresponding to the design cooling load, which

accords well with the predicted value with the relative error

Fig. 17 shows the comparison of inlet and outlet air

temperature difference between conventional natural ventila-

tion and solar-enhanced natural ventilation. It is concluded

through experiments that the average temperature difference

between the inlet and the outlet of the air channel is 2.6 8Cwhen the hot water temperature is 59.15 8C (Fig. 17(a)).However, it is only 0.6 8C for the conventional naturalventilation mode (Fig. 17(b)). Therefore, the stack pressure

built up by solar hot water is about four times of that formed in

the conventional natural ventilation. Under otherwise identical

conditions, the natural ventilation air flow rate is in proportion

to the square root of stack pressure. As a result, the natural

ventilation air flow rate induced by stack pressure is doubled.

Table 3

Summarization of solar-powered adsorption air-conditioning system experiments

Month/year

(mm/yy)

Average ambient

temperature (8C)Daily solar

insolation (MJ/m2)

Solar collecting

efficiency (%)

Refrigerating

output (kW)

Average

system COP

Average

solar COP

06/2005 29.86 17.71 35.64 10.29 0.29 0.11

07/2005 33.77 18.96 37.41 11.23 0.36 0.12

08/2005 31.89 17.24 38.02 10.77 0.32 0.11

X.Q. Zhai et al. / Energy and Buildings 39 (2007) 985993992of 2.8%.

3.4. Natural ventilation performance

The hot water in the storage tank is pumped to the finned

tube heat exchangers placed inside the air channel, where the

air is heated through free convection, which leads to the

increase of stack pressure. We lay a strong emphasis on the

measurement of the temperature difference between inlet and

outlet of the air channel due to the fact that it is in proportion to

stack pressure.

Experimental results of two days with similar ambient

temperature (10 8C) and daily solar insolation (17 MJ/m2) arechosen to compare the performance of solar-enhanced natural

ventilation with conventional natural ventilation. Fig. 16 shows

the variations of supply and back water temperature of finned

tube heat exchanger. It is seen that the average supply water

temperature is 59.15 8C, which is main factor to determine theperformance of solar-powered natural ventilation. Also can be

seen is that the temperature difference between supply and back

water nearly maintains 3 8C during whole operation.Fig. 16. Variations of supply and back water temperature of finned tube heat

exchanger.Fig. 17. Variation of air temperature difference between inlet and outlet of air

channel. (a) Solar-enhanced natural ventilation mode. (b) Conventional natural

ventilation mode.

Experimental results show that 68% of the days in transition

seasons were either sunny days or cloudy days, during which

the system was switched to enhance natural ventilation for the

purpose of consuming surplus hot water besides hot water

supply. The average natural ventilation air change rate induced

by solar hot water is 3 ACH with regard to the involved space.

3.5. Summary of all-year operation of the solar-powered

integrated energy system

From September 2004 to August 2005, the solar-powered

integrated energy system has been continuously in operation

under different modes according to different seasons. Based on

all-the-year-round experimental data, it is concluded that solar

fraction for the system in winter is 56%, correspondingly, 72%

in s

util

wei

sea

4. C

W

sys

(2) Under the climate condition of Shanghai, 150 m2 vacuum

tube solar collector arrays can be used to satisfy heating and

air-conditioning for covered area of 460 m2. In addition,

they are capable of inducing natural ventilation by stack

pressure and supplying hot water for the office building.

The solar-powered integrated energy system can take on

about 70% of the yearly building load regarding the

involved space.

Acknowledgements

This work is supported by the state Key Fundamental

Research Program under the contract No. G2000026309 P.R.C.,

and the Shanghai Commission of Science and Technology

under the contract No. 03DZ12012.

X.Q. Zhai et al. / Energy and Buildings 39 (2007) 985993 993utilization ratio of solar system. As a brief summary, it is

wished to emphasize the significant points of this work in the

following.

(1) For the first time, we put adsorption cooling technology into

practice in solar-powered air-conditioning system of green

building. The solar adsorption air-conditioning system

operates efficiently during 8 working hours under typical

sunny weather condition. The corresponding average

electric COP exceeds 8; furthermore, the maximal value

reaches 10. Solar-powered air-conditioning therefore

becomes practical because of utilization of evacuated

tubular solar collectors which are widely available in the

market.tion

of summer and 68% in transition seasons. Then themean annual

ization ratio of the system nearly reaches 70% through

ghted average calculation of solar fractions in different

sons and the corresponding days.

onclusion

e design and construct a solar-powered integrated energy

tem involving heating, air-conditioning, natural ventila-

and hot water supplying, which realizes high integration

olar thermal technologies, and therefore increasesReferences

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Solar integrated energy system for a green buildingIntroductionIntegrated solar energy system and the green buildingIntegration of solar collectors and green buildingDesign of solar-powered integrated energy systemFlow diagram of the integrated solar energy systemAdsorption chillerFloor heating pipeFinned tube heat exchangerData acquisition and control system

Performance of solar-powered integrated systemInstantaneous efficiency of solar collector arraysFloor radiation heating performanceAir-conditioning performanceNatural ventilation performanceSummary of all-year operation of the solar-powered integrated energy system

ConclusionAcknowledgementsReferences