Operating Control Modes Of Temperature And Humidity Control Ground-Source Heat Pump System

Cooling-dominated institutional buildings served by ground-source heat pump (GSHP) systems generally reject more heat to a closed ground-loop heat exchanger (GLHE) than they extract over the annual cycle. This unbalance may result in a significantly larger GLHE than would be required for a system with annually balanced heat rejection and extraction. So-called independent temperature and humidity control hybrid GSHP (HGSHP) system can control temperature and humidity separately to reduce system first cost and to improve system performance. For the cooling-dominated building, the GSHP take sensible heat load only so that it can reduce the use of borehole fields. Degradation of the heat pump performance is avoided by offsetting the annual load unbalance in the bore field. Moreover different control strategies and different operational parameter significantly affect the operation performance of HGSHP. A comparative study is presented that investigates restoration of the buried exit water temperature in a hybrid ground-source heat pump experiment system, which is easy and convenience and propitious to the application of GSHP in China.This thesis designs a common ground-Source Heat Pump System and a Hybrid Ground-Source Heat Pump System for a given building located in a given region. Through the relationship between buried exit water temperature and the system performance, the study analyzed and compared economical quality of different operation modes.First of all, the air-conditioning load of the building is calculated. Being cooling load dominated, the building calculated in this thesis is an office building located in Shanghai, and it is suitable for the temperature and humidity control hybrid GSHP system.Secondly, the mathematics modes have been established of the heat pump and vertical ground heat exchanger, which are the essential parts of the HGSHP systems. A transient heat transfer model of the soil temperature field around a vertical U-tube of ground source heat pump was established. The numerical simulation was obtained by using MATLAB software. The energy consumption in summer of the whole systems is simulated in hour by hour basis.Thirdly, several designs with different inverse condition time of the HGSHP are made. This paper got the date of four different conditions in summer by experiment. By comparing the date of experiment with the date of theory, its correctness can be verified. The influences of different inverse condition time are investigated, which can provide basis for further research, meanwhile, the corresponding changing curves are provided.Finally, according to the same building used for the simulation of hybrid ground source heat pump system and the general ground source heat pump system, this paper studied with the hour-by-hour simulation in summer, calculate the temperature of buried exit water, the COP and running costs. By comparison chart, the study has provided general methodology and advices for optimal design and operation of such HGSHP systems in this thesis.Hybrid GSHP can slow down the rise of exit water temperature and reduce heat accumulation so that it can solve unbalance of load. The temperature of buried exit water will be lower if the inverse condition closer to next day. The hybrid GSHP has higher COP, lower energy consumption and lower initial investment.