| Solar energy reserves are rich,clean and environmental,and are an ideal alternative to fossil fuels,but its intermittent and random and other shortcomings greatly affect the investment cost and the use effects of solar hot water system.The heat capacity and the thermal performance of soil as excellent natural regenerator are good,but its thermal conductivity is low,thus area of the ground heat exchanger demanded.When the buried pipes continuously absorb from the soil,the soil temperature will drop significantly,which is not conducive to the efficient and steady operation of the ground source heat pump heating system in the long term.In consideration of the above problems,a solar-ground source heat pump system both supplying hot water and heating was designed,which can realize the advantages of the two systems each other.The simulation models of the electric auxiliary heating solar hot water system,the ground source heat pump heating system individually and the solar-ground source heat pump system were also established,the models were simulated and the results were analyzed.The results show that:(1)hot water tank temperature should be controlled below 60℃,the design value of the collector area,hot water tank volume,and the starting/stopping temperature difference of circulating pump are reasonable;(2)the horizontal buried pipe type ground source heat pump separate heating system is affected largely by the outdoor environment temperature influence,and its soil temperature restoration ability is strong,so it is not necessary to replenish heat to the soil;in order to improve COP of the heat pump,it may be appropriate to increase the depth of buried pipe or add insulation layer above the horizontal buried pipes.Horizontal buried pipe depth is reasonable;(3)vertical buried pipe type ground source heat pump separate heating system is influenced greatly by the buried pipe depth and spacing.To ensure efficient and steady operation of the system chronicly,it is needed to complyment heat to the soil or increase the depth or the spacing of buried pipe.The depth of vertical and the horizontal spacing are reasonable;(4)the influence of the depth and distance to the ground source heat pump system will be reduced when the solar energy is heat up.Solar guarantee rate is reasonable;(5)the heating temperature has a greater impact on the collector efficiency and heat pump COP,the impact will gradually highlight after noon,and has a less inflence on the average temperature.The heating temperature of 64℃ is feasible.Meanwhile,the expressway service area buildings in Yulin was token as the research object,and the three schemes were compared whit annual cost and system COP which are the horizontal independent supply type,the vertical independent supply type and the vertical combined supply type of supplying hot water and heating,through the TRNSYS simulation analysis,and the influence of electricity price on the economic analysis was discussed.The results showed that:(1)the three schemes are all feasible;(2)the investment cost: the first one>the second one>the third one,the annual operating cost: the first one<the second one<the third one.Taking them into account,the annual cost: the first one<the second one<the third one;(3)the system COP: the first scheme<the second scheme<the third scheme;(4)when the annual cost and the system COP are considered,the first type is superior to the second type,the second type has an advantage over the third type,and the higher the electricity price(when over 0.3 yuan/kWh),the greater the superiority. |
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