A large number of seawater-source heat pump systems (SWHP) have been used in residential and commercial buildings in coastal areas due to the attractive advantages of high efficiency and environmental friendliness. To overcome the disadvantages of the open loop SWHP in winter of cold regions, a closed loop SWHP system with casted heat exchanger (CHE) is presented in this paper. The CHE is consisted of pipes immersed in the seawater and used for transferring heat between the seawater and the heat exchanger pipes of the SWHP. In addition, two mathematical models that described heat transfer process of CHE in the icing and non-icing conditions in winter have been developed and validated by an experimental study. The temperature distributions along the CHE were compared between the experimental data and numerical simulation results. The relative error is less than 5%. As a result, application of SWHP systems with CHE in coastal areas in China is feasible due to the favorable geographical conditions and environment.
In the area of using renewable energy, promoting the efficiency of seawater source heat pump plays an important part. Several nontraditional technologies are can be used in the new seawater source heat pump system. As for the intake system, infiltration intake technology is introduced, which can increase the supply temperature of sea water and thus raise the efficiency of the system. And as for the terminals, a new-style PVC low temperature water flowing radiant heating (LTWFRH) system is used to match the temperature characteristics of seawater source. After the optimization of the whole system, the seawater source heat pump can be more efficiency and thus saving more energy, considering the energy conservation effect of seawater source heat pump itself.
Using cheap and available natural flake graphite with high crystallinity and mesophase pitch as raw materials, graphite block materials with high bulk density, highly preferred orientation and high thermal conductivity, were prepared by a hot-press molding at mild temperatures and subsequent carbonization and graphitization treatments at high temperatures. XRD, SEM and PLM analyses indicate that the prepared graphite block has a highly preferred structural orientation, the graphitic layers of the graphite flakes inside are clearly oriented perpendicular to the hot-pressing direction. The components of various sized flake graphite and different types of pitch binders, and the proportions of raw materials, as well as the preparation process parameters (including hot-pressing temperature and pressure, heat treatment temperature, etc.), have great influences on the room-temperature in-plane thermal conductivity of the resultant graphite blocks. Graphitized blocks prepared from 86wt% NG (+32 mesh) and 14wt% AR mesophase pitch through hot-pressed at 500℃ at a fixed pressure of 10 MPa for 5 h and subsequently underwent 1000 ℃ carbonization and 2800℃ graphitization, have a good comprehensive thermophysical property. Their bulk density reaches above 1.91 g/m 3 , and room-temperature in-plane thermal conductivity is measured as high as 550 W/(m•K), and improved to 620 W/(m•K) after 3000℃ graphitization treatment.
The recirculating cooling water treatment process of low carbon & environmental protection adopts advanced design concepts of passive and energy saving and emission reduction. This process will be used widely in fossil-fueled power plant, which uses municipal reclaimed water or coal mine drainage. The operation results show that the effluent quality is stable, the concentration ratio is higher and the recirculating cooling water quality is better than the design criteria. It meets the safety and economic operation of units.
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