Experimental investigation on system with combination of ground-source heat pump and solar collector

Abstract

This paper presents the heating performance and energy distribution of a system with the combination of ground-source heat pump and solar collector or a solar-assisted ground-source heat pump system (SAGSHPS) by calculation and experiment. The results show that the average absolute error is less than 0.6 °C and the relative error is less than 5% under the pulse load when the analytical solution to the 2-D solid cylindrical source model is used for the SAGSHPS. The coefficient of performance (COP) of the SAGSHPS is 2.95–4.70. The average fluid temperature in the borehole heat exchanger can increase by 3 °C with the assistance of solar collector, which will improve the COP of the heat pump by approximately 10% from the experimental data. The energy contributions to the total heating load of soil, electricity and solar are 56.30%, 36.87% and 6.83%, respectively.

Keywords

ground-source heat pump / solar energy / heating performance / borehole heat exchanger

References

[1] Alkhamis T M, El-Khazali R, Kablan M M, et al. Heating of a biogas reactor using a solar energy system with temperature control unit[J]. Solar Energy, 2000, 69(3): 239-247.

[2] Penrond E B, Prasanna K V. Design of a flat plate collector for a solar earth heat pump[J]. Solar Energy, 1962, 6(1): 9-22.

[3] Chiasson A D. Advances in Modeling of Ground-Source Heat Pump Systems[D]. 1999 168

[4] Ozgener O, Hepbasli A. Experimental performance analysis of a solar assisted ground-source heat pump greenhouse heating system[J]. Energy and Buildings, 2005, 37(1): 101-110.

[5] Stojanović B, Akander J. Build-up and long-term performance test of a full-scale solar-assisted heat pump system for residential heating in Nordic climatic conditions[J]. Applied Thermal Engineering, 2010, 30(2/3): 188-195.

[6] Bi Y, Guo T, Zhang L, et al. Solar and ground source heat-pump system[J]. Applied Energy, 2004, 78(2): 231-245.

[7] Yang W, Shi M, Dong Hua. Numerical simulation of the performance of a solar-earth source heat pump system[J]. Applied Thermal Engineering, 2006, 26(17/18): 2367-2376.

[8] Yang W, Chen Z, Shi Mingheng. The alternate operation characteristics of a solar-ground source heat pump system[J]. Journal of Southeast University, 2010, 26(2): 327-332.

[9] Bakirci K, Ozyurt O, Comakli K, et al. Energy analysis of a solar-ground source heat pump system with vertical closed-loop for heating applications[J]. Energy, 2011, 36(5): 3224-3232.

[10] Chen X, Yang H, Lu L, et al. Experimental studies on a ground coupled heat pump with solar thermal collec tors for space heating[J]. Energy, 2011, 36(8): 5292-5300.

[11] Chen X, Lu L, Yang Hongxin. Long term operation of a solar assisted ground coupled heat pump system for space heating and domestic hot water[J]. Energy and Buildings, 2011, 43(8): 1835-1844.

[12] Chen X, Yang Hongxin. Performance analysis of a proposed solar assisted ground coupled heat pump system[J]. Applied Energy, 2012, 97, 888-896.

[13] Wang X, Zheng M, Zhang W, et al. Experimental study of a solar-assisted ground-coupled heat pump system with solar seasonal thermal storage in severe cold areas[J]. Energy and Buildings, 2010, 42(11): 2104-2110.

[14] Elisabeth K, Goran H, Bengt P. Optimization of systems with the combination of ground-source heat pump and solar collectors in dwellings[J]. Energy, 2010, 35(6): 2667-2673.

[15] Wang E, Fung Alan S, Qi C, et al. Performance prediction of a hybrid solar ground-source heat pump system[J]. Energy and Buildings, 2012, 47, 600-611.

[16] Ingersoll L R, Plass H J. Theory of the ground pipe heat source for the heat pump[J]. ASHVE Trans, 1948, 47, 339-348.

[17] Carslaw H S, Jaeger J C. Conduction of Heat in Solids[M]. 1959, 2nd ed, London, UK: Oxford University Press.

[18] Ingersoll L R, Zobel O J, Ingersoll A C. Heat Conduction with Engineering, Geological and Other Applications[M]. 1954, New York: Mc Graw-Hill 325

[19] Deerman J D, Kavanaugh S P. Simulation of vertical Utube ground-coupled heat pump systems using the cylindrical heat source solution[J]. ASHRAE Trans, 1991, 97, 287-294.

[20] Eskilson P. Thermal Analysis of Heat Extraction Boreholes[D]. 1987, Sweden: Department of Mathematical Physics, University of Lund.

[21] Diao N R, Zeng H Y, Fang Z H. Improvement in modeling of heat transfer in vertical ground heat exchangers[J]. HVAC and R Research, 2004, 10(4): 459-470.

[22] Marcotte D, Pasquier P. Fast fluid and ground temperature computation for geothermal ground-loop heat exchanger systems[J]. Geothermics, 2008, 37(6): 651-665.

[23] Bandos T V, Montero Fernández E, et al. Finite line-source model for borehole heat exchangers: Effect of vertical temperature variations[J]. Geothermics, 2009, 38(2): 263-270.

[24] Carslaw H S, Jaeger J C. Conduction of Heat in Solids[M]. 1947, Oxford, UK: Oxford University Press 510

[25] Mei V C, Emerson C J. New approach for analysis of ground-coil design for applied heat pump systems[J]. ASHRAE Trans, 1985, 91, 1216-1224.

[26] Kavanaugh S P. Simulation and Experimental Verification of Vertical Ground-Coupled Heat Pump Systems[D]. 1986, Stillwater, USA: Oklahoma State University.

[27] Lei T K. Development of a computational model for a ground-coupled heat exchanger[J]. ASHRAE Trans, 1993, 99(1): 149-159.

[28] Muraya N K, O’Neal D L, Heffington W M. Thermal interference of adjacent legs in vertical U-tube heat exchanger for a ground-coupled heat pump[J]. ASHRAE Trans, 1996, 102, 12-21.

[29] Rottmayer S P, Beckman W A, Mitchell J W. Simulation of a single vertical U-tube ground heat exchanger in an infinite medium[J]. ASHRAE Trans, 1997, 103, 651-659.

[30] Thornton J W, Hughes P J, McDowell T P, et al. Residential vertical geothermal heat pump system models: Calibration to data[J]. ASHRAE Trans, 1997, 103, 660-674.

[31] Yavuzturk C, Spitler J D, Rees S J. A transient twodimensional finite volume model for the simulation of vertical U-tube ground heat exchangers[J]. ASHRAE Trans, 1999, 105, 465-474.

[32] Yavuzturk C, Spitler J D. A short time step response factor model for vertical ground loop heat exchangers[J]. ASHRAE Trans, 1999, 105, 475-485.

[33] Lee C K, Lam H N. Computer simulation of borehole ground heat exchangers for geothermal heat pump systems[J]. Renewable Energy, 2008, 33(6): 1286-1296.

[34] Zhu J, Li H, Zhang Wei. Numerical simulation and optimization of phase change heat storage process with spiral pipe[J]. Journal of Tianjin University (Science and Technology), 2012, 45(10): 875-880.

[35] Man Y, Yang H, Diao N, et al. A new model and analytical solutions for borehole and pile ground heat exchangers[J]. International Journal of Heat and Mass Transfer, 2010, 53(13/14): 2593-2601.

[36] Hellstrom G. Ground Heat Storage: Thermal Analysis of Duct Storage Systems[D]. 1991, Sweden: Department of Mathematical Physics, University of Lund.

[37] Diao N, Fang Zhaohong. Buried Pipe and Ground-Source Heat Pump Technology[M]. 2006, Beijing, China: Higher Education Press.

[38] Wang H, Qi C, Du H, et al. Thermal performance of borehole heat exchanger under groundwater flow: A case study from Baoding[J]. Energy and Buildings, 2009, 41(12): 1368-1373.