The Study On The Heating Systems And The Energy Resources Configurations Of Greenhouses With High Geothermal Utilization Ratio

The potential of geothermal greenhouse developments in China is very large, which plays a great role in relaxing the conventional energy shortage and improving the ecological environment. Geothermal utilization ratio (GUR) shows the levels of energy saving, environment protecting and economic efficiency in the geothermal greenhouse heating system. So to study the ways for increasing the GUR and to found a heating system model with high GUR for geothermal greenhouses can give some theory guiding in designing a heating system, which contributes to the sustainable development of geothermal greenhouse industry.This paper focuses on the universally existing problems in geothermal greenhouse heating systems, takes the greenhouse characteristics and the geothermal characteristics into account, deeply studys the key technologies to increase the GUR, such as geothermal fluid storage, peaking system and multi-step utilization of geothermal fluid. Based on these, a multiplex heating system model of geothermal greenhouse is established and guidance on energy configuration for geothermal greenhouse is raised by the thermodynamic analysis and economic analysis. With an example analysis, the model's technology feasibility and economical applicability are proved.New low-cost practical geothermal water storage equipment is designed by studing the structure, the antileakage and antiseep technologies of geothermal water storage tank, by studing the thermal insulation forms of its water surface in experiment, and by analysising the construction of its heat losses.Using the no unit comprehensive formulas that describe a cumulative heating requirement curve, we derive some mathematical expressions, such as the cumulative heating load in heating period, the cumulative peak load in heating period, the beginning temperature of peaking, the peak days, and the geothermal energy utilization efficiency in heating period. Defining the load efficiency in heating period, the designed peak load ratio and the cumulative peak load ratio can simplify the computations about cumulative loads. The value range of the cumulative peak load ratio is determined by the analysis of geothermal energy utilization efficiency in heating period and the analysis of the economics characteristics. The load efficiency in heating period and the maximum cumulative peak load ratio of 38 citys in China is presented. The influence of the designed peak load ratio to heating scal is analysised. By the comparation of several peak heat sources, the priority sequence is determined.Some main heating methods in geothermal greenhouse is introduced in this paper, where definitude geothermal heating methods'configuration principles, discuss geothermal waste heat utilization's energy saving potential, and study water source heat pumps'positive result in multi-step utilization of geothermal fluid.A multiplex heating system model of geothermal greenhouse is established. Some formulas on energy configuration by the model are derived, and the priority sequence of energy configuration forms is determined by economic analysis. The model can be simplified and evolved, that can be utilized broadly in geothermal greenhouses and other geothermal heating systems.