Solar-assisted Ground-source Heat Pump Research Articles

05/02782 Experimental investigation of the performance of a solar-assisted ground-source heat pump system for greenhouse heating

05/02782 Experimental investigation of the performance of a solar-assisted ground-source heat pump system for greenhouse heating

05/01265 Experimental performance analysis of a solar assisted ground-source heat pump greenhouse heating system

05/01265 Experimental performance analysis of a solar assisted ground-source heat pump greenhouse heating system

Experimental investigation of the performance of a solar-assisted ground-source heat pump system for greenhouse heating

The main objective of the present study is to investigate the performance characteristics of a solar-assisted ground-source heat pump system (SAGSHPS) for greenhouse heating with a 50 m vertical 1¼ in nominal diameter U-bend ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir (568 degree days cooling, base: 22°C, 1226 degree days heating, base: 18°C), Turkey. Based upon the measurements made in the heating mode, the heat extraction rate from the soil is found to be, on average, 54.08 Wm−1 of bore depth, while the required borehole length in meter per kW of heating capacity is obtained as 12.57. The entering water temperature to the unit ranges from 8.2 to 16.2°C, with an average value of 9.1°C. The greenhouse air is at a maximum day temperature of 25°C and night temperature of 14°C with a relative humidity of 40%. The heating coefficient of performance of the heat pump (COPHP) is about 2.13 at the end of a cloudy day, while it is about 2.84 at the end of sunny day and fluctuates between these values in other times. The COP values for the whole system are also obtained to be 5–15% lower than COPHP. Copyright © 2004 John Wiley & Sons, Ltd.

Exergoeconomic analysis of a solar assisted ground-source heat pump greenhouse heating system

EXCEM analysis may prove useful to investigators in engineering and other disciplines due to the methodology are being based on the quantities exergy, cost, energy and mass. The main objective of the present study is to investigate between capital costs and thermodynamic losses for devices in solar assisted ground-source heat pump greenhouse heating system (SAGSHPGHS) with a 50 m vertical 32 mm nominal diameter U-bend ground heat exchanger. This system was designed and installed at the Solar Energy Institute, Ege University, Izmir, Turkey. Thermodynamic loss rate-to-capital cost ratios are used to show that, for components and the overall system, a systematic correlation appears to exist between capital cost and exergy loss (total or internal), but not between capital cost and energy loss or external exergy loss. This correlation may imply that devices in successful air conditioning are configured so as to achieve an overall optimal design, by appropriately balancing the thermodynamic (exergy-based) and economic characteristics of the overall system and its devices. The results may (i) provide useful insights into the relations between thermodynamics and economics, both in general and for SAGSHPGHS, (ii) help demonstrate the merits of second-law analysis. It is observed from the results that the maximum exergy destructions in the system particularly occur due to the electrical, mechanical and isentropic efficiencies and emphasize the need for paying close attention to the selection of this type of equipment, since components of inferior performance can considerably reduce the overall performance of the system. In conjunction with this, the total exergy losses values are obtained to be from 0.010 kW to 0.480 kW for the system. As expected, the largest energy and exergy losses occur in the greenhouse and compressor. The ratio of thermodynamic loss rate to capital cost values are obtained for a range from 0.035 to 1.125.

Performance analysis of a solar-assisted ground-source heat pump system for greenhouse heating: an experimental study

This study investigates the performance characteristics of a solar-assisted ground-source (geothermal) heat pump system (SAGSHPS) for greenhouse heating with a 50 m vertical 32 mm nominal diameter U-bend ground heat-exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir (568 degree days cooling, base: 22 °C, 1226 degree days heating, base: 18 °C), Turkey. Based upon the measurements made in the heating mode from the 20th of January till 31st of March 2004, the heat extraction rate from the soil is found to be, on average, 57.78 W/m of bore depth, while the required borehole length in metre per kW of capacity is obtained as 11.92. Design practices in Turkey normally call for U-bend depths between 11 and 13 m/kW of heating. The entering water temperature to the unit ranges from 8.2 to 16.2 °C, with an average value of 14 °C. The greenhouse air has a maximum day temperature of 31.05 °C and night temperature of 14.54 °C with a relative humidity of 40.35%. The heating coefficient of performance of the heat pump (COP HP) is about 2.00 at the end of a cloudy day, while it is about 3.13 at the end of sunny day and fluctuates between these values in other times. The COP values for the whole system are also obtained to be 5–20% lower than COP HP. The clearness index during experimental period is computed as average 0.56. At the same period, Cucumus sativus cv. pandora F 1 was raised, and product quality was improved with the climatic conditions in the designed SAGSHPS. However, experimental results show that monovalent central heating operation (independent of any other heating system) cannot meet the overall heat loss of the greenhouse if the ambient temperature is very low. The bivalent operation (combined with other heating system) can be suggested as the best solution in Mediterranean and Aegean regions of Turkey.

Experimental performance analysis of a solar assisted ground-source heat pump greenhouse heating system

Ground-source heat pumps (GSHPs), also known as geothermal heat pumps (GHPs), are recognized to be outstanding heating, cooling and water heating systems, and have been used since 1998 in the Turkish market. Greenhouses also have important economical potential in Turkey’s agricultural sector. In addition to solar energy gain, greenhouses should be heated during nights and cold days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of heat pumps with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future. The main objective of the present study is to investigate to the performance characteristics of a solar assisted ground-source heat pump greenhouse heating system (SAGSHPGHS) with a 50 m vertical 1 × 1/4 in. nominal diameter U-bend ground heat exchanger using exergy analysis method. This system was designed and constructed in Solar Energy Institute of Ege University, Izmir, Turkey. The exergy transports between the components and the destructions in each of the components of the SAGSHPGHS are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The heating coefficient of performances of the ground-source heat pump unit and the overall system are obtained to be 2.64 and 2.38, respectively, while the exergetic efficiency of the overall system is found to be 67.7%.

134 Voltage-dependent facilitation of k + current in fibroblast cells transformed with ngk 1(kv 1.2) k + channel cDNA

In the present research, a methodology is proposed to optimize the solar collector area and ground heat exchanger length for achieving higher COP of Solar Assisted Ground Source Heat Pump (SAGSHP) system using Taguchi method and utility concept. Four operating parameters for solar collector and four parameters for ground heat exchanger have been selected with mixed level variation using an L18 (21, 37) orthogonal array. The key parameters such as solar collector area, ground heat exchanger length and COP of the SAGSHP system are optimized to predict the best levels of operating parameters for maximum COP of SAGSHP system. Lower the better concept has been used for the solar collector area and ground heat exchanger length whereas higher the better concept has been employed for the COP of SAGSHP system and the results have been analyzed for the optimum conditions using signal-to-noise (SN) ratio and ANOVA method. Computations were carried out for 18 experimental trial runs by considering 2 ton heating load in winter season. The optimum COP for SAGSHP was estimated to be 4.23 from the utility concept, which is 8.74% higher than the optimum COP predicted by Taguchi optimization. Optimization of solar collector area and ground heat exchanger length by the utility concept has shown only about 2.3% reduction in area and 1.6% reduction in length respectively compared to those values optimized by the Taguchi method.

133 Significance of L-type Ca 2+ channel and Ca 2+-atpase for oscillation of cytosolic Ca 2+ in GH 3 cells

In the present research, a methodology is proposed to optimize the solar collector area and ground heat exchanger length for achieving higher COP of Solar Assisted Ground Source Heat Pump (SAGSHP) system using Taguchi method and utility concept. Four operating parameters for solar collector and four parameters for ground heat exchanger have been selected with mixed level variation using an L18 (21, 37) orthogonal array. The key parameters such as solar collector area, ground heat exchanger length and COP of the SAGSHP system are optimized to predict the best levels of operating parameters for maximum COP of SAGSHP system. Lower the better concept has been used for the solar collector area and ground heat exchanger length whereas higher the better concept has been employed for the COP of SAGSHP system and the results have been analyzed for the optimum conditions using signal-to-noise (SN) ratio and ANOVA method. Computations were carried out for 18 experimental trial runs by considering 2 ton heating load in winter season. The optimum COP for SAGSHP was estimated to be 4.23 from the utility concept, which is 8.74% higher than the optimum COP predicted by Taguchi optimization. Optimization of solar collector area and ground heat exchanger length by the utility concept has shown only about 2.3% reduction in area and 1.6% reduction in length respectively compared to those values optimized by the Taguchi method.