SIMULATION OF SOLAR COOLING SYSTEM FOR A

RESIDENTIAL BUILDING IN SOUTH AFRICA

Presented by Doudou N. Luta

Outline Introduction Case of study Simulation description Simulation results Economic analysis Conclusion References

Introduction

What is solar cooling system?Why solar cooling system?What is absorption cooling systemObjective of the paper

IntroductionWhat is solar cooling system?Solar cooling systems refer to the use of solar energy to power a cooling system.

Why solar cooling system? HVAC equipment are one of the major consumers of

electricity which result to an increasing cost of electricity bill

Conventional HVAC lead to environmental concerns due to the use of some refrigerants such as CFC (ChloroFluoroCarbon) and HCFC (HydroChloroFluoroCarbon)

Need of alternative clean energy sources to drive cooling units

Introduction (suite)What is an absorption cooling system?

An heat driven heat pumpObjective of the paper

Analyses the performance of an absorption cooling system driven by solar energy for a residential building located in south Africa

Case of study

Description of the case of studySimulation of Cape town weather data for

October 2013

Case of study Description of the case of study

We have considered an unknown residential building located in cape town with a cooling load 15kW

The simulation is based on the month of October 2013

The simulation tool used is Insel Software

Case of study (suite)Simulation of Cape Town weather data

Figure1 Solar Radiation simulation scheme

Peak daily radiation687 W/m2 of October

2013

Case of study (suite)D

aily

radi

atio

n in

W/m

2

Days of OctoberFigure 2 Daily global radiation of Cape Town versus hours in October 2013

respectively

Simulation description

Figure 3 Solar absorption air conditioning system simulation scheme

Simulation results

Collectors outlet temperature in ºC

Evap

orat

or r

efri

gera

tion

ca

paci

ty in

kW

Collectors outlet temperature in ºC

Evap

orat

or o

utle

t te

mpe

ratu

re

in º

CFigure 4 Refrigerating capacity of the

evaporator as function of the collectors’ outlet temperature

Figure 5 Evaporator temperature as function of the collectors outlet

temperature

Economic analysis The costs of solar absorption cooling systems are still very high compared to

conventional cooling systems. However, solar absorption cooling systems present the advantage of saving energy and money in term of payback.

A 15 kW solar absorption cooling system with 0.7 Coefficient of Performance will normally run at 15 kW x 0.7 = 10.5 kW

Assuming that this cooling system is operating 10 hours per day, the energy save for 10 hours would be 10.5 kW x 10 = 105 kWh. Under the current Cape Town electricity tariff rate, this cooling system would be charged:

105 kWh x 173.28 c/kWh [8] = R18.1944 per day

This means that R18.1944 is save every day, R545.832 every month and R6549.984 every year.

The average lifetime of the major solar cooling system components are generally approximated to 20 years [9]. Over this lifetime, the amount of money save would be R130999.68

Apart from the fact that the price of collectors and absorption cooling system components are still very high compared to conventional cooling systems, solar absorption cooling systems represents a good alternative cooling option.

Due the weather variation, in order the meet the cooling load requirement, the system must include an additional backup energy source. For a residential building, adding a backup source of energy increases the cost of installation and the overall size of the system compared to conventional cooling units. However, when comparing both systems in term of the long term running cost, solar absorption cooling systems present the advantage of saving money and energy.

Conclusion

Reference[1] D. M. Tagare, Electric Power Generation: The Changing Dimension, New Jersey: John

Wiley & Sons, 2011. [2] V. Mittal, K. Kasana and N. Thakur, “The study of solar absorption air-conditioning

systems,” Journal of Energy in Southern Africa, vol. 16, no. 4, pp. 59-66, 2005. [3] Z. Sayadi, S. El May, M. Bourouis and A. Bellagi, “Technical and economic analysis of a

solar assisted air conditioning systems,” IEEE Conference, pp. 331-338, 2010. [4] Y. Fan, L. Luo and B. Souyri, “Review of solar sorption refrigeration technologies:

Development and applications,” Renewable and Sustainable Energy Reviews 11, p. 1758–1775, 2007.

[5] ASHRAE, Handbook of HVAC Systems and Equipements, ASHRAE, 2008.

[6] C. A. Balaras, G. Grossman, H.-M. Henning, C. A. Infante Ferreira, E. Podesser, L. Wang and E. Wiemken, “Solar air conditioning in Europe—an overview,” Renewable and Sustainable Energy Reviews 11, pp. 299-314, 2007.

[7] M. H. Muzaffar and F. A. Ghaith, “Design and simulation of solar powered cooling system in UAE,” in Conf. on Future Trends in Structural, Civil, Environmental and Mechanical Engineering.

[8] C. o. C. Town, “www.capetown.gov.za,” 16 March 2014. [Online]. Available: https://www.capetown.gov.za/en/Pages/default.aspx. [Accessed 16 March 2014].

[9] L. C. Haw, K. Sopian and Y. Sulaiman, “An Overview of Solar Assisted Air-Conditioning System An Overview of Solar Assisted Air-Conditioning System,” in International Conference of Energy and Environnement, 2009.

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