Potential mapping of ground source heat pump systems considering groundwater pumping

The pumping of groundwater near GHEs improves the performance of GSHP systems due to the advection of the induced roundwater flow when the hydraulic conductivity of the formation is favorable. To quantify the effect, we first carried out performance analysis of a GSHP heating system under the influence of groundwater pumping. The heating operation data clearly showed the improved COP of the heat pump when the groundwater is pumped. To evaluate the effect of groundwater pumping, we then collected the water pumping data from the groundwater snow-melting system in Akita City, Japan and input those data to the existing field-scale numerical groundwater flow and heat transport model of the area. The model was run to calculate the groundwater velocity and temperature in the area under the influence of groundwater pumping. Then, the output from the model was used for developing another numerical model, small-scale GHE model, which can estimate the minimum necessary GHE length for a Japanese standard detached house at several locations in the area. The GHE length data were mapped using GIS software to generate the GSHP potential map under the influence of groundwater pumping. The comparison between the potential maps with and without groundwater pumping clearly indicated the contribution of water pumping in reducing the GHE length and the initial cost of GSHP systems

Field tests and numerical simulation of a novel thermal response test equipment for water wells

The objective of this study is to develop a novel thermal response test (TRT) equipment that can be applied to existing water wells instead of borehole heat exchangers (BHEs). Accordingly, field tests were conducted using new and conventional equipment to estimate the vertical distribution of ground thermal conductivity. The result showed that the estimated thermal conductivity profile was higher than the reference profile obtained using conventional equipment. The temperature behavior in the well was considered to be unstable due to natural convection because the heating time was 4 hours, which is not long enough. Next, a numerical model of the water well including the novel equipment was developed, and the model was validated through history matching by using the temperature change in each depth. Finally, the TRT was simulated for two days using the model, and the simulated thermal conductivity profile was similar to the reference profile except near the end of the heated section. This result indicates that a more accurate thermal conductivity profile can be obtained by increasing the heating time until approximately 1.5 days

Determinants of Severity in Dilated Cardiomyopathy : The Gap of Tricuspid and Mitral Valve Opening

Objectives: The purpose of this study is to analyze factors that influence the gap ofopening timing between the mitral valve (MV) and the tricuspid valve (TV) inpatients with dilated cardiomyopathy (DCM).Background: The DCM patients with heart failure often show shorter left ventricular(LV) isovolumic relaxation time (IRT) and longer right ventricular (RV) IRT, whichmay influence the gap of opening timing between TV and MV.Method: We evaluated consecutive 34 patients with DCM. The time between QRSinitial and TV opening (Q-T time), and that between QRS initial and MV opening (QMtime) were measured by pulsed Doppler recording of each ventricular inflow. Thetime interval between MV and TV opening (M-T time) was determined by subtractingQ-M time from Q-T time. In addition, the other Doppler time intervals including preejectionalperiod, ejection time, IRT were determined. We analyzed the relationbetween Doppler time intervals and factors including NYHA classification and rightsidedcardiac pressure.Result: There is significant relationship (p <0.001) between M-T time and PCWP(r=0.65), and NYHA (rs=0.67), respectively. The Ll IRT determined by subtractionof LV IRT from RV IRT, correlated significantly with M-T time (r=0.83, p<O.OOl),however, the difference between LV and RV in PEP and ET did not correlatedsignificantly with M-T time.Conclusion: The gap of opening timing between TV and MV, determined as M-T time,correlates strongly with LlIRT and also the severity of congestive heart failure in DCMpatients