| OCR Text |
Show 12 Jacket losses exhibit the opposite trend: the average value of 6.7 percent at high firing rate is less than the average of 7.6 percent at low firing rate. Higher jacket losses at low firing rate are credible from the standpoint that 1) jacket losses are expressed as a percentage of gross firing rate and 2) the internal temperatures which drive the jacket losses are reduced only slightly by reducing firing rate. Thus, while the absolute magnitude of jacket losses is probably reduced at low firing rate, the relative magnitude generally increases. Second-generation system results. The first-generation prototype provided valuable design and operating experience. However, the observed steady-state efficiencies were not acceptable. Accordingly, the design was modified with the hope of reducing both stack and jacket losses. These hopes were realized in a brief test with the second-generation prototype during which an average steady-state efficiency of 35.1 percent was measured. Average stack and jacket losses of 12.1 and 2.8 percent compared favorably with the results obtained previously. No trends in efficiency or stack or jacket losses with firing rate were observed with the second-generation device over the narrow range tested. CONCLUSIONS AND FUTURE WORK An integrated burner system incorporating a radiant impingement burner, a finned reflux boiler and a crossflow recuperator was designed and tested. The design of the system was strongly influenced by its ultimate use as the energy source for a residential absorption heat pump. The steady-state efficiency goal of 85 percent was approached with a first-generation device and met with an improved, second-generation prototype. Volume constraints and the desire to avoid condensing operation preclude the attainment of significantly higher efficiencies. Future efforts will be directed toward evaluating the transient behavior of the system and adapting it to the outdoor environment. Ignition characteristics, response time and pollutant emissions during cold, warm |
