Abstract
A critical mathematical model can lead to reliable prediction of the dynamic behaviour of a system. In this study, a robust and accurate data acquisition system (DAS) was employed to monitor the electrical energy consumption of a 150-L geyser and 150-L split and integrated types air source heat pump (ASHP) water heaters. This study equally focused on using the multiple linear regression models to correlate the coefficient of performance (COP) of the split and the integrated types ASHP water heaters to the difference between the hot water set-point temperature and the ambient temperature (Ts − Ta) and the relative humidity (RH). The models derived for both the split and integrated types ASHP water heaters had good determination coefficients of 0.900 and 0.901, respectively. The ReliefF algorithm tests showed that in either of the systems, the RH was a secondary factor while the (Ts − Ta) was a primary factor. The cost of DAS used in obtaining the data required for the model derivation was relatively low but of high measurement accuracy.
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig1_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig2_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig3_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig4_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig5_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig6_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig7_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig8_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig9_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig10_HTML.png)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs12053-019-09802-1/MediaObjects/12053_2019_9802_Fig11_HTML.png)
Similar content being viewed by others
References
Aguilar, C., White, D. J., & Ryan, D. L. (2005). Domestic water heating and water heater energy consumption in Canada. Canadian Building Energy End-Use Data and Analysis Centre.
Bich, W., Cox, M. G., & Harris, P. M. (2006). Evolution of the “guide to the expression of uncertainty in measurement”. Metrologia, 43(4), S161–S166.
Bodzin, S. (1997). Air-to-water heat pumps for the home. Home Energy, (4), 14.
Coleman, H. W., & Steel, W. G. (1999). Experimentation and uncertainty analysis for engineers (2nd ed.p. P4). New York: Wiley.
Cooper, C. & Prinsloo, J. (2002). Digest of South African energy statistics. See also: http://www.dme.gov.za/pdfs/energy/planning/digest_energy_06.pdf. Date of access: 30 Aug 2002.
De Swardt, C. A., & Meyer, J. P. (2001). A performance comparison between an air-source and a ground-source reversible heat pump. International Journal of Energy Research, 25(10), 899–910.
Eskom (2010) Integrated Demand Management. www.eskom.co.za/home/about. Date of access: 30 Jul 2010.
Eskom (2014). Heat pumps, http://www.eskom.co.za/sites/idm/HeatPumps/Pages/HeatPumps.aspx. Date of access: 12 Jul 2014.
Eskom report (2011). Residential heat pump rebate programme. In Energy efficiency measurement & verification practices. Pp. 127–135.
Fardoun, F., Ibrahim, O. & Zoughaib, A., (2011). Dynamic modeling of an air source heat pump water heater. In 10th International Energy Agency Heat Pump Conference 2011-HPC 2011 (pp. 12-p).
Fu, L., Ding, G., & Zhang, C., Jr. (2003). Dynamic simulation of air-to-water dual-mode heat pump with screw compressor. Applied Thermal Engineering, 23, 1629–1645.
Goswami, D. Y., & Kreith, F. e. (2007). Energy conversion. CRC press.
Ito, S., Miura, N., & Wang, K. (1999). Performance of a heat pump using direct expansion solar collectors. Solar Energy, 65(3), 189–196.
Kima, M., Kim, M. S., & Chung, J. D., Jr. (2004). Transient thermal behavior of a water heater system driven by a heat pump. International Journal of Refrigeration, 27, 415–421.
Klein-Trnsys, S. A. (1990). A transient system simulation program-University of Wisconsin. Solar Energy Laboratory.
Levins, W. P. (1982). Estimated seasonal performance of a heat pump water heater including effects of climate and in-house location (No. ORNL/CON-81). TN (USA): Oak Ridge National Lab..
MacArthur, J. W., & Grald, E. W., Jr. (1989). Unsteady compressible two-phase flow model for predicting cyclic heat pump performance and a comparison with experimental data. International Journal of Refrigeration, 12(1), 29–41.
Meyer, J. P., & Tshimankinda, M. (1998). Domestic hot water consumption in South African townhouses. Energy Conversion and Management, 39(7), 679–684.
Morrison, G. L., Anderson, T., & Behnia, M. (2004). Seasonal performance rating of heat pump water heaters. Solar Energy, 76(1), 147–152.
Ravina, M., Panepinto, D., Zanetti, M. C., & Genon, G. (2017). Environmental analysis of a potential district heating network powered by a large-scale cogeneration plant. Environmental Science & Pollution Research, 24(15), 13424–13436.
Ravina, M., Panepinto, D., & Zanetti, M. C. (2018). DIDEM- an integrated model for comparative health damage costs calculation of air pollution. Atmospheric Environment, 173, 81–95.
Robnik-Šikonja, M., & Kononenko, I. (2003). Theoretical and empirical analysis of ReliefF and RReliefF. Machine Learning, 53(1–2), 23–69.
Tangwe, S. L., & Simon, M. (2018). Evaluation of performance of air source heat pump water heaters using the surface fitting models: 3D mesh plots and 2D multi contour plots simulation. Thermal Science and Engineering Progress, 5, 516–523.
Tangwe, S., Simon, M., & Meyer, E. (2014). Mathematical modelling and simulation application to visualize the performance of retrofit heat pump water heater under first hour heating rating. Renewable Energy Journal, 72(December 2014), 203–211.
Tangwe, S., Simon, M., Mamphweli, S., Makaka, G., & Meyer, E. (2015). Performance optimization of air source heat pump water heater. Southern African Journal of Energy, 26(1), 96–105 ISSN 2413-3051.
Tangwe, S., Simon, M., & Meyer, E. (2016). Design of a heat pump water heater performance monitoring system: to determine performance of a split type system. Engineering Journal of Technology and Design., 14(4), 739–751.
Tangwe, S. L., Simon, M., & Mhundwa, R. (2018). The performance of split and integrated types of air-source heat pump water heaters in South Africa. Journal of Energy in Southern Africa, 29(2), 12–20.
Techarungpaisan, P., Theerakulpisut, S., & Priprem, S., Jr. (2007). Modeling of a split type air conditioner with integrated water heater. Energy Conversion and Management, 48, 1222–1237.
Acknowledgements
We acknowledge South Africa electricity supply utility (Eskom) for their financial support in the purchase of the equipment used for the execution of the research.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Tangwe, S.L., Simon, M. Development of simplified benchmark models to predict the coefficient of performance of residential air source heat pump water heaters in South Africa. Energy Efficiency 12, 1821–1835 (2019). https://doi.org/10.1007/s12053-019-09802-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12053-019-09802-1